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<div class="Title">Solaris ZFS Administration Guide</div>
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<p class="toc level1 tocsp">
<a href="bookinfo.html">Document Information</a>
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<p class="toc level1 tocsp">
<a href="preface.html">Preface</a>
</p>
<p class="toc level1 tocsp">
<a href="chapter.html">1. Solaris ZFS
File System (Introduction)</a>
</p>
<p class="toc level1 tocsp">
<a href="chapter2.html">2. Getting
Started With ZFS</a>
</p>
<p class="toc level1 tocsp">
<a href="chapter3.html">3. ZFS and Traditional File System Differences</a>
</p>
<p class="toc level1 tocsp">
<a href="chapter4.html">4. Managing
ZFS Storage Pools</a>
</p>
<div class="onpage">
<p class="toc level1 tocsp">
<a href="chapter5.html">5. Managing
ZFS File Systems</a>
</p>
<p class="toc level2">
<a href="#gamnq">Creating and Destroying ZFS File Systems</a>
</p>
<p class="toc level2">
<a href="#gazss">Introducing ZFS Properties</a>
</p>
<p class="toc level2">
<a href="#gazsu">Querying ZFS File System Information</a>
</p>
<p class="toc level2">
<a href="#gayns">Managing ZFS Properties</a>
</p>
<p class="toc level2">
<a href="#gaynd">Mounting and Sharing ZFS File Systems</a>
</p>
<p class="toc level2">
<a href="#gazvb">ZFS Quotas and Reservations</a>
</p>
</div>
<p class="toc level1 tocsp">
<a href="chapter6.html">6. Working
With ZFS Snapshots and Clones</a>
</p>
<p class="toc level1 tocsp">
<a href="chapter7.html">7. Using
ACLs to Protect ZFS Files</a>
</p>
<p class="toc level1 tocsp">
<a href="chapter8.html">8. ZFS
Delegated Administration</a>
</p>
<p class="toc level1 tocsp">
<a href="chapter9.html">9. ZFS
Advanced Topics</a>
</p>
<p class="toc level1 tocsp">
<a href="chapter10.html">10. ZFS
Troubleshooting and Data Recovery</a>
</p>
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<div class="MainContent">
<a name="gavwq"></a>Chapter 5<h3>Managing
ZFS File Systems</h3>
<p>This chapter provides detailed information about managing Solaris<sup>TM</sup> ZFS file systems. Concepts such as hierarchical file system layout,
property inheritance, and automatic mount point management and share interactions
are included in this chapter.</p>
<p>A ZFS file system is a lightweight POSIX file system that is built on
top of a storage pool. File systems can be dynamically created and destroyed
without requiring you to allocate or format any underlying space. Because
file systems are so lightweight and because they are the central point of
administration in ZFS, you are likely to create many of them.</p>
<p>ZFS file systems are administered by using the <tt>zfs</tt> command.
The <tt>zfs</tt> command provides a set of subcommands that perform
specific operations on file systems. This chapter describes these subcommands
in detail. Snapshots, volumes, and clones are also managed by using this command,
but these features are only covered briefly in this chapter. For detailed
information about snapshots and clones, see <a href="chapter6.html#gavvx">Chapter&nbsp;6,
Working With ZFS Snapshots and Clones</a>. For detailed information about
emulated volumes, see <a href="chapter9.html#gaypf">ZFS Volumes</a>.</p>
<hr>
<p>
<b>Note - </b>
<p>The term <b>dataset</b> is used in this chapter
as a generic term to refer to a file system, snapshot, clone, or volume.</p>

</p>
<hr>
<p>The following sections are provided in this chapter:</p>
<ul>
<li>
<p>
<a href="chapter5.html#gamnq">Creating and Destroying ZFS File
Systems</a>
</p>

</li>
<li>
<p>
<a href="chapter5.html#gazss">Introducing ZFS Properties</a>
</p>

</li>
<li>
<p>
<a href="chapter5.html#gazsu">Querying ZFS File System Information</a>
</p>

</li>
<li>
<p>
<a href="chapter5.html#gayns">Managing ZFS Properties</a>
</p>

</li>
<li>
<p>
<a href="chapter5.html#gaynd">Mounting and Sharing ZFS File Systems</a>
</p>

</li>
<li>
<p>
<a href="chapter5.html#gazvb">ZFS Quotas and Reservations</a>
</p>

</li>
<li>
<p>
<a href="chapter6.html#gbchx">Saving and Restoring ZFS Data</a>
</p>

</li>
</ul>

<a name="gamnq"></a>
<h3>Creating and Destroying ZFS File Systems</h3>
<p>ZFS file systems can be created and destroyed by using the <tt>zfs
create</tt> and <tt>zfs destroy</tt> commands.</p>
<ul>
<li>
<p>
<a href="chapter5.html#gazsf">Creating a ZFS File System</a>
</p>

</li>
<li>
<p>
<a href="chapter5.html#gammq">Destroying a ZFS File System</a>
</p>

</li>
<li>
<p>
<a href="chapter5.html#gamnn">Renaming a ZFS File System</a>
</p>

</li>
</ul>
<a name="gazsf"></a>
<h3>Creating a ZFS File System</h3>
<p>ZFS file systems are created by using the <tt>zfs create</tt> command.
The <tt>create</tt> subcommand takes a single argument: the name
of the file system to create. The file system name is specified as a path
name starting from the name of the pool:</p>
<p>
<tt><i>pool-name/[filesystem-name/]filesystem-name</i></tt>
</p>
<p>The pool name and initial file system names in the path identify the
location in the hierarchy where the new file system will be created. All the
intermediate file system names must already exist in the pool. The last name
in the path identifies the name of the file system to be created. The file
system name must satisfy the naming conventions defined in <a href="chapter.html#gbcpt">ZFS Component Naming Requirements</a>.</p>
<p>In the following example, a file system named <tt>bonwick</tt> is
created in the <tt>tank/home</tt> file system.</p>
<pre>
<tt># <tt>zfs create tank/home/bonwick</tt></tt>
</pre>
<p>ZFS automatically mounts the newly created file system if it is created
successfully. By default, file systems are mounted as <tt><i>/dataset</i></tt>,
using the path provided for the file system name in the <tt>create</tt> subcommand.
In this example, the newly created <tt>bonwick</tt> file system
is at <tt>/tank/home/bonwick</tt>. For more information about
automanaged mount points, see <a href="chapter5.html#gaztn">Managing ZFS Mount
Points</a>.</p>
<p>For more information about the <tt>zfs create</tt> command,
see zfs1M.</p>
<p>You can set file system properties when the file system is created.</p>
<p>In the following example, a mount point of <tt>/export/zfs</tt> is
specified and is created for the <tt>tank/home</tt> file system.</p>
<pre>
<tt># <tt>zfs create -o mountpoint=/export/zfs tank/home</tt></tt>
</pre>
<p>For more information about file system properties, see <a href="chapter5.html#gazss">Introducing ZFS Properties</a>.</p>

<a name="gammq"></a>
<h3>Destroying a ZFS File System</h3>
<p>To destroy a ZFS file system, use the <tt>zfs destroy</tt> command.
The destroyed file system is automatically unmounted and unshared. For more
information about automatically managed mounts or automatically managed shares,
see <a href="chapter5.html#gbala">Automatic Mount Points</a>.</p>
<p>In the following example, the <tt>tabriz</tt> file system
is destroyed.</p>
<pre>
<tt># <tt>zfs destroy tank/home/tabriz</tt></tt>
</pre>
<hr>
<p>
<b>Caution - </b>
<p>No confirmation prompt appears with the <tt>destroy</tt> subcommand.
Use it with extreme caution.</p>

</p>
<hr>
<p>If the file system to be destroyed is busy and so cannot be unmounted,
the <tt>zfs destroy</tt> command fails. To destroy an active file
system, use the <tt>f</tt> option. Use this option with caution as
it can unmount, unshare, and destroy active file systems, causing unexpected
application behavior.</p>
<pre>
<tt># <tt>zfs destroy tank/home/ahrens</tt>
cannot unmount 'tank/home/ahrens': Device busy

# <tt>zfs destroy -f tank/home/ahrens</tt></tt>
</pre>
<p>The <tt>zfs destroy</tt> command also fails if a file system
has children. To recursively destroy a file system and all its descendents,
use the <tt>r</tt> option. Note that a recursive destroy also destroys
snapshots so use this option with caution.</p>
<pre>
<tt># <tt>zfs destroy tank/ws</tt>
cannot destroy 'tank/ws': filesystem has children
use '-r' to destroy the following datasets:
tank/ws/billm
tank/ws/bonwick
tank/ws/maybee

# <tt>zfs destroy -r tank/ws</tt></tt>
</pre>
<p>If the file system to be destroyed has indirect dependents, even the
recursive destroy command described above fails. To force the destruction
of <b>all</b> dependents, including cloned file systems outside
the target hierarchy, the <tt>R</tt> option must be used. Use extreme
caution with this option.</p>
<pre>
<tt># <tt>zfs destroy -r tank/home/schrock</tt>
cannot destroy 'tank/home/schrock': filesystem has dependent clones
use '-R' to destroy the following datasets:
tank/clones/schrock-clone

# <tt>zfs destroy -R tank/home/schrock</tt></tt>
</pre>
<hr>
<p>
<b>Caution - </b>
<p>No confirmation prompt appears with the <tt>f</tt>, <tt>r</tt>, or <tt>R</tt> options so use these options carefully.</p>

</p>
<hr>
<p>For more information about snapshots and clones, see <a href="chapter6.html#gavvx">Chapter&nbsp;6, Working With ZFS Snapshots and Clones</a>.</p>

<a name="gamnn"></a>
<h3>Renaming a ZFS File System</h3>
<p>File systems can be renamed by using the <tt>zfs rename</tt> command.
Using the <tt>rename</tt> subcommand can perform the following operations:</p>
<ul>
<li>
<p>Change the name of a file system </p>

</li>
<li>
<p>Relocate the file system to a new location within the ZFS
hierarchy</p>

</li>
<li>
<p>Change the name of a file system and relocate it with the
ZFS hierarchy</p>

</li>
</ul>
<p>The following example uses the <tt>rename</tt> subcommand
to do a simple rename of a file system:</p>
<pre>
<tt># <tt>zfs rename tank/home/kustarz tank/home/kustarz_old</tt></tt>
</pre>
<p>This example renames the <tt>kustarz</tt> file system to <tt>kustarz_old</tt>. </p>
<p>The following example shows how to use <tt>zfs rename</tt> to
relocate a file system.</p>
<pre>
<tt># <tt>zfs rename tank/home/maybee tank/ws/maybee</tt></tt>
</pre>
<p>In this example, the <tt>maybee</tt> file system is relocated
from <tt>tank/home</tt> to <tt>tank/ws</tt>. When
you relocate a file system through rename, the new location must be within
the same pool and it must have enough space to hold this new file system.
If the new location does not have enough space, possibly because it has reached
its quota, the rename will fail.</p>
<p>For more information about quotas, see <a href="chapter5.html#gazvb">ZFS
Quotas and Reservations</a>.</p>
<p>The rename operation attempts an unmount/remount sequence for the file
system and any descendent file systems. The rename fails if the operation
is unable to unmount an active file system. If this problem occurs, you will
need to force unmount the file system.</p>
<p>For information about renaming snapshots, see <a href="chapter6.html#gbion">Renaming
ZFS Snapshots</a>.</p>


<a name="gazss"></a>
<h3>Introducing ZFS Properties</h3>
<p>Properties are the main mechanism that you use to control the behavior
of file systems, volumes, snapshots, and clones. Unless stated otherwise,
the properties defined in the section apply to all the dataset types.</p>
<ul>
<li>
<p>
<a href="chapter5.html#gazsy">ZFS Read-Only Native Properties</a>
</p>

</li>
<li>
<p>
<a href="chapter5.html#gazsd">Settable ZFS Native Properties</a>
</p>

</li>
<li>
<p>
<a href="chapter5.html#gdrcw">ZFS User Properties</a>
</p>

</li>
</ul>
<p>Properties are divided into two types, native properties and user defined
properties. Native properties either export internal statistics or control
ZFS file system behavior. In addition, native properties are either settable
or read-only. User properties have no effect on ZFS file system behavior,
but you can use them to annotate datasets in a way that is meaningful in your
environment. For more information on user properties, see <a href="chapter5.html#gdrcw">ZFS User Properties</a>.</p>
<p>Most settable properties are also inheritable. An inheritable property
is a property that, when set on a parent, is propagated down to all of its
descendents.</p>
<p>All inheritable properties have an associated source. The source indicates
how a property was obtained. The source of a property can have the following
values:</p>
<dl>
<dt>
<tt>local</tt>
</dt>
<dd>
<p>A <tt>local</tt> source indicates that the property
was explicitly set on the dataset by using the <tt>zfs set</tt> command
as described in <a href="chapter5.html#gazsp">Setting ZFS Properties</a>.</p>

</dd>
<dt>
<tt>inherited from</tt> <tt><i>dataset-name</i></tt>
</dt>
<dd>
<p>A value of <tt>inherited from</tt> <tt><i>dataset-name</i></tt> means that the property was inherited from the named ancestor.</p>

</dd>
<dt>
<tt>default</tt>
</dt>
<dd>
<p>A value of <tt>default</tt> means that the property
setting was not inherited or set locally. This source is a result of no ancestor
having the property as source <tt>local</tt>.</p>

</dd>
</dl>
<p>The following table identifies both read-only and settable native ZFS
file system properties. Read-only native properties are identified as such.
All other native properties listed in this table are settable. For information
about user properties, see <a href="chapter5.html#gdrcw">ZFS User Properties</a>.</p>
<a name="gcfgr"></a>
<h6>ZFS Native Property Descriptions</h6>
<table cellpadding="8" cellspacing="2" border="1">
<tr>
<th valign="" align="">
<p>Property Name</p>

</th><th valign="" align="">
<p>Type</p>

</th><th valign="" align="">
<p>Default Value</p>

</th><th valign="" align="">
<p>Description</p>

</th>
</tr>
<tr>
<td valign="" align="">
<p>
<tt>aclinherit</tt>
</p>

</td><td valign="" align="">
<p>String</p>

</td><td valign="" align="">
<p>
<tt>secure</tt>
</p>

</td><td valign="" align="">
<p>Controls how ACL entries are inherited when files and directories are
created. The values are <tt>discard</tt>, <tt>noallow</tt>, <tt>secure</tt>, and <tt>passthrough</tt>. For a description of
these values, see <a href="chapter7.html#gbaaz">ACL Property Modes</a>.</p>

</td>
</tr>
<tr>
<td valign="" align="">
<p>
<tt>aclmode</tt>
</p>

</td><td valign="" align="">
<p>String</p>

</td><td valign="" align="">
<p>
<tt>groupmask</tt>
</p>

</td><td valign="" align="">
<p>Controls how an ACL entry is modified during a <tt>chmod</tt> operation.
The values are <tt>discard</tt>, <tt>groupmask</tt>, and <tt>passthrough</tt>. For a description of these values, see <a href="chapter7.html#gbaaz">ACL Property Modes</a>.</p>

</td>
</tr>
<tr>
<td valign="" align="">
<p>
<tt>atime</tt>
</p>

</td><td valign="" align="">
<p>Boolean</p>

</td><td valign="" align="">
<p>
<tt>on</tt>
</p>

</td><td valign="" align="">
<p>Controls whether the access time for files is updated when they are
read. Turning this property off avoids producing write traffic when reading
files and can result in significant performance gains, though it might confuse
mailers and other similar utilities.</p>

</td>
</tr>
<tr>
<td valign="" align="">
<p>
<tt>available</tt>
</p>

</td><td valign="" align="">
<p>Number</p>

</td><td valign="" align="">
<p>N/A</p>

</td><td valign="" align="">
<p>Read-only property that identifies the amount of space available to
the dataset and all its children, assuming no other activity in the pool.
Because space is shared within a pool, available space can be limited by
various factors including physical pool size, quotas, reservations, or other
datasets within the pool.</p>
<p>This property can also be referenced by its shortened column name, <tt>avail</tt>.</p>
<p>For more information about space accounting, see <a href="chapter3.html#gbchp">ZFS
Space Accounting</a>.</p>

</td>
</tr>
<tr>
<td valign="" align="">
<p>
<tt>canmount</tt>
</p>

</td><td valign="" align="">
<p>Boolean</p>

</td><td valign="" align="">
<p>on</p>

</td><td valign="" align="">
<p>Controls whether the given file system can be mounted with the <tt>zfs</tt> <tt>mount</tt> command. This property can be set on any
file system and the property itself is not inheritable. However, when this
property is set, a mountpoint can be inherited to descendent file systems,
but the file system itself is never mounted. For more information, see <a href="chapter5.html#gdrcf">The canmount Property</a>.</p>

</td>
</tr>
<tr>
<td valign="" align="">
<p>
<tt>casesensitivity</tt>
</p>

</td><td valign="" align="">
<p>String</p>

</td><td valign="" align="">
<p>
<tt>sensitive</tt>
</p>

</td><td valign="" align="">
<p>This
property indicates whether the file name matching algorithm used by the file
system should be <tt>casesensitive</tt>,<tt> caseinsensitive</tt>,
or allow a combination of both styles of matching (<tt>mixed</tt>).
The default value for this property is <tt>sensitive</tt>. Traditionally,
UNIX and POSIX file systems have case-sensitive file names.</p>
<p>The <tt>mixed</tt> value for this property indicates the file system can support
requests for both case-sensitive and case-insensitive matching behavior. Currently,
case-insensitive matching behavior on a file system that supports mixed behavior
is limited to the Solaris CIFS server product. For more information about
using the <tt>mixed</tt> value, see <a href="chapter5.html#gftgr">The
casesensitivity Property</a>.</p>
<p>Regardless of the <tt>casesensitivity</tt> property setting, the file system preserves the case of the name
specified to create a file. This property cannot be changed after the file
system is created.</p>

</td>
</tr>
<tr>
<td valign="" align="">
<p>
<tt>checksum</tt>
</p>

</td><td valign="" align="">
<p>String</p>

</td><td valign="" align="">
<p>
<tt>on</tt>
</p>

</td><td valign="" align="">
<p>Controls the checksum used to verify data integrity. The default value
is <tt>on</tt>, which automatically selects an appropriate algorithm,
currently <tt>fletcher2</tt>. The values are <tt>on, off, fletcher2</tt>, <tt>fletcher4</tt>, and <tt>sha256</tt>. A
value of <tt>off</tt> disables integrity checking on user data.
A value of <tt>off</tt> is not recommended.</p>

</td>
</tr>
<tr>
<td valign="" align="">
<p>
<tt>compression</tt>
</p>

</td><td valign="" align="">
<p>String</p>

</td><td valign="" align="">
<p>
<tt>off</tt>
</p>

</td><td valign="" align="">
<p>Controls the compression algorithm used for this dataset. Currently,
you can select <tt>lzjb</tt>, <tt>gzip</tt>, or <tt>gzip-</tt><tt><i>N</i></tt>. Enabling compression on a file system
with existing data only compresses new data. Existing data remains uncompressed.</p>
<p>This property can also be referred to by its shortened column name, <tt>compress</tt>.</p>

</td>
</tr>
<tr>
<td valign="" align="">
<p>
<tt>compressratio</tt>
</p>

</td><td valign="" align="">
<p>Number</p>

</td><td valign="" align="">
<p>N/A</p>

</td><td valign="" align="">
<p>Read-only property that identifies the compression ratio achieved for
this dataset, expressed as a multiplier. Compression can be turned on by running <tt>zfs set compression=on</tt> <tt><i>dataset</i></tt>.</p>
<p>Calculated from the logical size of all files and the amount of referenced
physical data. Includes explicit savings through the use of the <tt>compression</tt> property.</p>

</td>
</tr>
<tr>
<td valign="" align="">
<p>
<tt>copies</tt>
</p>

</td><td valign="" align="">
<p>Number</p>

</td><td valign="" align="">
<p>1</p>

</td><td valign="" align="">
<p>Sets the number of copies of user data per file system. Available values
are 1, 2 or 3. These copies are in addition to any pool-level redundancy.
Space used by multiple copies of user data is charged to the corresponding
file and dataset and counts against quotas and reservations. In addition,
the <tt>used</tt> property is updated when multiple copies are
enabled. Consider setting this property when the file system is created because
changing this property on an existing file system only affects newly written
data.</p>

</td>
</tr>
<tr>
<td valign="" align="">
<p>
<tt>creation</tt>
</p>

</td><td valign="" align="">
<p>Number</p>

</td><td valign="" align="">
<p>N/A</p>

</td><td valign="" align="">
<p>Read-only property that identifies the date and time that this dataset
was created.</p>

</td>
</tr>
<tr>
<td valign="" align="">
<p>
<tt>devices</tt>
</p>

</td><td valign="" align="">
<p>Boolean</p>

</td><td valign="" align="">
<p>
<tt>on</tt>
</p>

</td><td valign="" align="">
<p>Controls the ability to open device files in the file system.</p>

</td>
</tr>
<tr>
<td valign="" align="">
<p>
<tt>exec</tt>
</p>

</td><td valign="" align="">
<p>Boolean</p>

</td><td valign="" align="">
<p>
<tt>on</tt>
</p>

</td><td valign="" align="">
<p>Controls whether programs within this file system are allowed to be
executed. Also, when set to <tt>off</tt>, <tt>mmap(2)</tt> calls
with <tt>PROT_EXEC</tt> are disallowed.</p>

</td>
</tr>
<tr>
<td valign="" align="">
<p>
<tt>mounted</tt>
</p>

</td><td valign="" align="">
<p>boolean</p>

</td><td valign="" align="">
<p>N/A</p>

</td><td valign="" align="">
<p>Read-only property that indicates whether this file system, clone, or
snapshot is currently mounted. This property does not apply to volumes. Value
can be either yes or no.</p>

</td>
</tr>
<tr>
<td valign="" align="">
<p>
<tt>mountpoint</tt>
</p>

</td><td valign="" align="">
<p>String</p>

</td><td valign="" align="">
<p>N/A</p>

</td><td valign="" align="">
<p>Controls the mount point used for this file system. When the <tt>mountpoint</tt> property is changed for a file system, the file system and any
children that inherit the mount point are unmounted. If the new value is <tt>legacy</tt>, then they remain unmounted. Otherwise, they are automatically
remounted in the new location if the property was previously <tt>legacy</tt> or <tt>none</tt>, or if they were mounted before the property was changed. In
addition, any shared file systems are unshared and shared in the new location.</p>
<p>For more information about using this property, see <a href="chapter5.html#gaztn">Managing ZFS Mount Points</a>.</p>

</td>
</tr>
<tr>
<td valign="" align="">
<p>
<tt>nbmand</tt>
</p>

</td><td valign="" align="">
<p>Boolean</p>

</td><td valign="" align="">
<p>off</p>

</td><td valign="" align="">
<p>Controls whether the file system should be mounted with <tt>nbmand</tt>
(Non-blocking mandatory) locks. This property is for CIFS clients only. Changes
to this property only take effect when the file system is unmounted
and remounted. </p>

</td>
</tr>
<tr>
<td valign="" align="">
<p>
<tt>normalization</tt>
</p>

</td><td valign="" align="">
<p>String</p>

</td><td valign="" align="">
<p>None</p>

</td><td valign="" align="">
<p>This property indicates whether a file system should perform a unicode
normalization of file names whenever two file names are compared, and
which normalization algorithm should be used. File names are always stored
unmodified, names are normalized as part of any comparison process. If this
property is set to a legal value other than <tt>none</tt>, and
the <tt>utf8only</tt> property was left unspecified, the <tt>utf8only</tt> property is automatically set to <tt>on</tt>. The default
value of the <tt>normalization</tt> property is <tt>none</tt>.
This property cannot be changed after the file system is created. </p>

</td>
</tr>
<tr>
<td valign="" align="">
<p>
<tt>origin</tt>
</p>

</td><td valign="" align="">
<p>String</p>

</td><td valign="" align="">
<p>N/A</p>

</td><td valign="" align="">
<p>Read-only property for cloned file systems or volumes that identifies
the snapshot from which the clone was created. The origin cannot be destroyed
(even with the <tt>r</tt> or <tt>f</tt> options) as long as
a clone exists.</p>
<p>Non-cloned file systems have an origin of none.</p>

</td>
</tr>
<tr>
<td valign="" align="">
<p>
<tt>quota</tt>
</p>

</td><td valign="" align="">
<p>Number (or <tt>none</tt>)</p>

</td><td valign="" align="">
<p>
<tt>none</tt>
</p>

</td><td valign="" align="">
<p>Limits the amount of space a dataset and its descendents can consume.
This property enforces a hard limit on the amount of space used, including
all space consumed by descendents, including file systems and snapshots. Setting
a quota on a descendent of a dataset that already has a quota does not override
the ancestor's quota, but rather imposes an additional limit. Quotas cannot
be set on volumes, as the <tt>volsize</tt> property acts as an
implicit quota.</p>
<p>For information about setting quotas, see <a href="chapter5.html#gazud">Setting
Quotas on ZFS File Systems</a>.</p>

</td>
</tr>
<tr>
<td valign="" align="">
<p>
<tt>readonly</tt>
</p>

</td><td valign="" align="">
<p>Boolean</p>

</td><td valign="" align="">
<p>
<tt>off</tt>
</p>

</td><td valign="" align="">
<p>Controls whether this dataset can be modified. When set to <tt>on</tt>,
no modifications can be made to the dataset.</p>
<p>This property can also be referred to by its shortened column name, <tt>rdonly</tt>.</p>

</td>
</tr>
<tr>
<td valign="" align="">
<p>
<tt>recordsize</tt>
</p>

</td><td valign="" align="">
<p>Number</p>

</td><td valign="" align="">
<p>
<tt>128K</tt>
</p>

</td><td valign="" align="">
<p>Specifies a suggested block size for files in the file system.</p>
<p>This property can also be referred to by its shortened column name, <tt>recsize</tt>. For a detailed description, see <a href="chapter5.html#gcfgv">The
recordsize Property</a>.</p>

</td>
</tr>
<tr>
<td valign="" align="">
<p>
<tt>referenced</tt>
</p>

</td><td valign="" align="">
<p>Number</p>

</td><td valign="" align="">
<p>N/A</p>

</td><td valign="" align="">
<p>Read-only property that identifies the amount of data accessible by
this dataset, which might or might not be shared with other datasets in the
pool.</p>
<p>When a snapshot or clone is created, it initially references the same
amount of space as the file system or snapshot it was created from, because
its contents are identical.</p>
<p>This property can also be referred to by its shortened column name, <tt>refer</tt>.</p>

</td>
</tr>
<tr>
<td valign="" align="">
<p>
<tt>refquota</tt>
</p>

</td><td valign="" align="">
<p>Number
(or none)</p>

</td><td valign="" align="">
<p>none</p>

</td><td valign="" align="">
<p>Sets
the amount of space that a dataset can consume. This property enforces a hard
limit on the amount of space used. This hard limit does not include space
used by descendents, such as snapshots and clones.</p>

</td>
</tr>
<tr>
<td valign="" align="">
<p>
<tt>refreservation</tt>
</p>

</td><td valign="" align="">
<p>Number
(or none)</p>

</td><td valign="" align="">
<p>
<tt>none</tt>
</p>

</td><td valign="" align="">
<p>Sets
the minimum amount of space that is guaranteed to a dataset, not including
descendents, such as snapshots and clones. When the amount of space that is
used is below this value, the dataset is treated as if it were taking up the
amount of space specified by <tt>refreservation</tt>. The <tt>refreservation</tt> reservation is accounted for in the parent datasets' space used,
and counts against the parent datasets' quotas and reservations.</p>
<p>If <tt>refreservation</tt> is set, a snapshot is only allowed if
enough free pool space is available outside of this reservation to accommodate
the current number of <b>referenced</b> bytes in the dataset.</p>
<p>This property can also be referred to by its shortened column name, <tt>refreserv</tt>.</p>

</td>
</tr>
<tr>
<td valign="" align="">
<p>
<tt>reservation</tt>
</p>

</td><td valign="" align="">
<p>Number (or none)</p>

</td><td valign="" align="">
<p>
<tt>none</tt>
</p>

</td><td valign="" align="">
<p>The minimum amount of space guaranteed to a dataset and its descendents.
When the amount of space used is below this value, the dataset is treated
as if it were using the amount of space specified by its reservation. Reservations
are accounted for in the parent datasets' space used, and count against the
parent datasets' quotas and reservations.</p>
<p>This property can also be referred to by its shortened column name, <tt>reserv</tt>.</p>
<p>For more information, see <a href="chapter5.html#gbdbb">Setting Reservations
on ZFS File Systems</a>.</p>

</td>
</tr>
<tr>
<td valign="" align="">
<p>
<tt>setuid</tt>
</p>

</td><td valign="" align="">
<p>Boolean</p>

</td><td valign="" align="">
<p>
<tt>on</tt>
</p>

</td><td valign="" align="">
<p>Controls whether the <tt>setuid</tt> bit is honored in the
file system.</p>

</td>
</tr>
<tr>
<td valign="" align="">
<p>
<tt>sharenfs</tt>
</p>

</td><td valign="" align="">
<p>String</p>

</td><td valign="" align="">
<p>
<tt>off</tt>
</p>

</td><td valign="" align="">
<p>Controls whether the file system is available over NFS, and what options
are used. If set to <tt>on</tt>, the <tt>zfs share</tt> command
is invoked with no options. Otherwise, the <tt>zfs share</tt> command
is invoked with options equivalent to the contents of this property. If set
to <tt>off</tt>, the file system is managed by using the legacy <tt>share</tt> and <tt>unshare</tt> commands and the <tt>dfstab</tt> file.</p>
<p>For more information on sharing ZFS file systems, see <a href="chapter5.html#gamnd">Sharing and Unsharing ZFS File Systems</a>.</p>

</td>
</tr>
<tr>
<td valign="" align="">
<p>
<tt>sharesmb</tt>
</p>

</td><td valign="" align="">
<p>Boolean</p>

</td><td valign="" align="">
<p>off</p>

</td><td valign="" align="">
<p>Controls whether the file system is shared by using the Solaris CIFS
service, and what options are to be used. A file system with the <tt>sharesmb</tt> property set to <tt>off</tt> is managed through traditional
tools, such as the <tt>sharemgr</tt> command. Otherwise, the file
system is automatically shared and unshared by using the <tt>zfs share</tt> and <tt>zfs unshare</tt> commands.</p>
<p>If the property is set to <tt>on</tt>, the <tt>sharemgr</tt> command
is invoked with no options. Otherwise, the <tt>sharemgr</tt> command
is invoked with options that are equivalent to the contents of this property.</p>

</td>
</tr>
<tr>
<td valign="" align="">
<p>
<tt>snapdir</tt>
</p>

</td><td valign="" align="">
<p>String</p>

</td><td valign="" align="">
<p>
<tt>hidden</tt>
</p>

</td><td valign="" align="">
<p>Controls whether the <tt>.zfs</tt> directory is hidden or
visible in the root of the file system. For more information on using snapshots,
see <a href="chapter6.html#gbciq">Overview of ZFS Snapshots</a>.</p>

</td>
</tr>
<tr>
<td valign="" align="">
<p>
<tt>type</tt>
</p>

</td><td valign="" align="">
<p>String</p>

</td><td valign="" align="">
<p>N/A</p>

</td><td valign="" align="">
<p>Read-only property that identifies the dataset type as <tt>filesystem</tt> (file
system or clone), <tt>volume</tt>, or <tt>snapshot</tt>.</p>

</td>
</tr>
<tr>
<td valign="" align="">
<p>
<tt>used</tt>
</p>

</td><td valign="" align="">
<p>Number</p>

</td><td valign="" align="">
<p>N/A</p>

</td><td valign="" align="">
<p>Read-only property that identifies the amount of space consumed by the
dataset and all its descendents.</p>
<p>For a detailed description, see <a href="chapter5.html#gcfgz">The used Property</a>.</p>

</td>
</tr>
<tr>
<td valign="" align="">
<p>
<tt>utf8only</tt>
</p>

</td><td valign="" align="">
<p>Boolean</p>

</td><td valign="" align="">
<p>Off</p>

</td><td valign="" align="">
<p>This property indicates whether a file system should reject file names
that include characters that are not present in the UTF-8 character code
set. If this property is explicitly set to <tt>off</tt>, the <tt>normalization</tt> property must either not be explicitly set or be set to <tt>none</tt>. The default value for the <tt>utf8only</tt> property
is <tt>off</tt>. This property cannot be changed after the file system is created.</p>

</td>
</tr>
<tr>
<td valign="" align="">
<p>
<tt>volsize</tt>
</p>

</td><td valign="" align="">
<p>Number</p>

</td><td valign="" align="">
<p>N/A</p>

</td><td valign="" align="">
<p>For volumes, specifies the logical size of the volume.</p>
<p>For a detailed description, see <a href="chapter5.html#gcfhk">The volsize
Property</a>.</p>

</td>
</tr>
<tr>
<td valign="" align="">
<p>
<tt>volblocksize</tt>
</p>

</td><td valign="" align="">
<p>Number</p>

</td><td valign="" align="">
<p>8 Kbytes</p>

</td><td valign="" align="">
<p>For volumes, specifies the block size of the volume. The block size
cannot be changed once the volume has been written, so set the block size
at volume creation time. The default block size for volumes is 8 Kbytes. Any
power of 2 from 512 bytes to 128 Kbytes is valid.</p>
<p>This property can also be referred to by its shortened column name, <tt>volblock</tt>.</p>

</td>
</tr>
<tr>
<td valign="" align="">
<p>
<tt>vscan</tt>
</p>

</td><td valign="" align="">
<p>Boolean</p>

</td><td valign="" align="">
<p>Off</p>

</td><td valign="" align="">
<p>Controls whether regular files should be scanned for viruses when a
file is opened and closed. In addition to enabling this property, a virus scanning service must also be
enabled for virus scanning to occur. The default value is <tt>off</tt>.</p>

</td>
</tr>
<tr>
<td valign="" align="">
<p>
<tt>zoned</tt>
</p>

</td><td valign="" align="">
<p>Boolean</p>

</td><td valign="" align="">
<p>N/A</p>

</td><td valign="" align="">
<p>Indicates whether this dataset has been added to a non-global zone.
If this property is set, then the mount point is not honored in the global
zone, and ZFS cannot mount such a file system when requested. When a zone
is first installed, this property is set for any added file systems.</p>
<p>For more information about using ZFS with zones installed, see <a href="chapter9.html#gayov">Using ZFS on a Solaris System With Zones Installed</a>.</p>

</td>
</tr>
<tr>
<td valign="" align="">
<p>
<tt>xattr</tt>
</p>

</td><td valign="" align="">
<p>Boolean</p>

</td><td valign="" align="">
<p>
<tt>on</tt>
</p>

</td><td valign="" align="">
<p>Indicates whether extended attributes are enabled or disabled for this
file system. The default value is <tt>on</tt>.</p>

</td>
</tr>
</table>
<a name="gazsy"></a>
<h3>ZFS Read-Only Native Properties</h3>
<p>Read-only native properties are properties that can be retrieved but
cannot be set. Read-only native properties are not inherited. Some native
properties are specific to a particular type of dataset. In such cases, the
particular dataset type is mentioned in the description in <a href="chapter5.html#gcfgr">Table&nbsp;5&ndash;1</a>.</p>
<p>The read-only native properties are listed here and are described in <a href="chapter5.html#gcfgr">Table&nbsp;5&ndash;1</a>.</p>
<ul>
<li>
<p>
<tt>available</tt>
</p>

</li>
<li>
<p>
<tt>creation</tt>
</p>

</li>
<li>
<p>
<tt>mounted</tt>
</p>

</li>
<li>
<p>
<tt>origin</tt>
</p>

</li>
<li>
<p>
<tt>compressratio</tt>
</p>

</li>
<li>
<p>
<tt>referenced</tt>
</p>

</li>
<li>
<p>
<tt>type</tt>
</p>

</li>
<li>
<p>
<tt>used</tt>
</p>
<p>For detailed information,
see <a href="chapter5.html#gcfgz">The used Property</a>.</p>

</li>
</ul>
<p>For more information on space accounting, including the <tt>used</tt>, <tt>referenced</tt>, and <tt>available</tt> properties, see <a href="chapter3.html#gbchp">ZFS Space Accounting</a>.</p>
<a name="gcfgz"></a>
<h4>The used Property</h4>
<p>The amount of space consumed by this dataset and all its descendents.
This value is checked against the dataset's quota and reservation. The space
used does not include the dataset's reservation, but does consider the reservation
of any descendent datasets. The amount of space that a dataset consumes from
its parent, as well as the amount of space that is freed if the dataset is
recursively destroyed, is the greater of its space used and its reservation.</p>
<p>When snapshots are created, their space is initially shared between
the snapshot and the file system, and possibly with previous snapshots. As
the file system changes, space that was previously shared becomes unique to
the snapshot, and counted in the snapshot's space used. Additionally, deleting
snapshots can increase the amount of space unique to (and used by) other snapshots.
For more information about snapshots and space issues, see <a href="chapter3.html#gayra">Out of Space Behavior</a>.</p>
<p>The amount of space used, available, or referenced does not take into
account pending changes. Pending changes are generally accounted for within
a few seconds. Committing a change to a disk using <tt>fsync(3c)</tt> or <tt>O_SYNC</tt> does not necessarily guarantee that the space usage information
will be updated immediately.</p>


<a name="gazsd"></a>
<h3>Settable ZFS Native Properties</h3>
<p>Settable native properties are properties whose values can be both retrieved
and set. Settable native properties are set by using the <tt>zfs set</tt> command,
as described in <a href="chapter5.html#gazsp">Setting ZFS Properties</a> or
by using the <tt>zfs create</tt> command as described in <a href="chapter5.html#gazsf">Creating a ZFS File System</a>. With the exceptions
of quotas and reservations, settable native properties are inherited. For
more information about quotas and reservations, see <a href="chapter5.html#gazvb">ZFS
Quotas and Reservations</a>.</p>
<p>Some settable native properties are specific to a particular type of
dataset. In such cases, the particular dataset type is mentioned in the description
in <a href="chapter5.html#gcfgr">Table&nbsp;5&ndash;1</a>. If not specifically
mentioned, a property applies to all dataset types: file systems, volumes,
clones, and snapshots.</p>
<p>The settable properties are listed here and are described in <a href="chapter5.html#gcfgr">Table&nbsp;5&ndash;1</a>.</p>
<ul>
<li>
<p>
<tt>aclinherit</tt>
</p>
<p>For a detailed
description, see <a href="chapter7.html#gbaaz">ACL Property Modes</a>.</p>

</li>
<li>
<p>
<tt>aclmode</tt>
</p>
<p>For a detailed description,
see <a href="chapter7.html#gbaaz">ACL Property Modes</a>.</p>

</li>
<li>
<p>
<tt>atime</tt>
</p>

</li>
<li>
<p>
<tt>canmount</tt>
</p>

</li>
<li>
<p>
<tt>casesensitivity</tt>
</p>

</li>
<li>
<p>
<tt>checksum</tt>
</p>

</li>
<li>
<p>
<tt>compression</tt>
</p>

</li>
<li>
<p>
<tt>copies</tt>
</p>

</li>
<li>
<p>
<tt>devices</tt>
</p>

</li>
<li>
<p>
<tt>exec</tt>
</p>

</li>
<li>
<p>
<tt>mountpoint</tt>
</p>

</li>
<li>
<p>
<tt>nbmand</tt>
</p>

</li>
<li>
<p>
<tt>normalization</tt>
</p>

</li>
<li>
<p>
<tt>quota</tt>
</p>

</li>
<li>
<p>
<tt>readonly</tt>
</p>

</li>
<li>
<p>
<tt>recordsize</tt>
</p>
<p>For a detailed
description, see <a href="chapter5.html#gcfgv">The recordsize Property</a>.</p>

</li>
<li>
<p>
<tt>refquota</tt>
</p>

</li>
<li>
<p>
<tt>refreservation</tt>
</p>

</li>
<li>
<p>
<tt>reservation</tt>
</p>

</li>
<li>
<p>
<tt>sharenfs</tt>
</p>

</li>
<li>
<p>
<tt>sharesmb</tt>
</p>

</li>
<li>
<p>
<tt>setuid</tt>
</p>

</li>
<li>
<p>
<tt>snapdir</tt>
</p>

</li>
<li>
<p>
<tt>vscan</tt>
</p>

</li>
<li>
<p>
<tt>utf8only</tt>
</p>

</li>
<li>
<p>
<tt>volsize</tt>
</p>
<p>For a detailed description,
see <a href="chapter5.html#gcfhk">The volsize Property</a>.</p>

</li>
<li>
<p>
<tt>volblocksize</tt>
</p>

</li>
<li>
<p>
<tt>zoned</tt>
</p>

</li>
</ul>
<a name="gdrcf"></a>
<h4>The canmount Property</h4>
<p>If this property is set to no, the file system cannot be mounted by
using the <tt>zfs mount</tt> or <tt>zfs mount</tt> <tt>a</tt> commands.
This property is similar to setting the <tt>mountpoint</tt> property
to <tt>none</tt>, except that the dataset still has a normal <tt>mountpoint</tt> property that can be inherited. For example, you can
set this property to no, establish inheritable properties for descendent file
systems, but the file system itself is never mounted nor it is accessible
to users. In this case, the parent file system with this property set to no
is serving as a <b>container</b> so that you can set attributes
on the container, but the container itself is never accessible.</p>
<p>In the following example, <tt>userpool</tt> is created and
the <tt>canmount</tt> property is set to off. Mount points for
descendent user file systems are set to one common mount point, <tt>/export/home</tt>. Properties that are set on the parent file system are inherited
by descendent file systems, but the parent file system itself is never mounted.</p>
<pre>
<tt># <tt>zpool create userpool mirror c0t5d0 c1t6d0</tt>
# <tt>zfs set canmount=off userpool</tt>
# <tt>zfs set mountpoint=/export/home userpool</tt>
# <tt>zfs set compression=on userpool</tt>
# <tt>zfs create userpool/user1</tt>
# <tt>zfs create userpool/user2</tt>
# <tt>zfs list -r userpool</tt>
NAME USED AVAIL REFER MOUNTPOINT
userpool 140K 8.24G 24.5K /export/home
userpool/user1 24.5K 8.24G 24.5K /export/home/user1
userpool/user2 24.5K 8.24G 24.5K /export/home/user2</tt>
</pre>

<a name="gftgr"></a>
<h4>The casesensitivity Property</h4>
<p>This property indicates whether the file name matching algorithm used
by the file system should be <tt>casesensitive</tt>, <tt>caseinsensitive</tt>, or allow a combination of both styles of matching (<tt>mixed</tt>).</p>
<p>When a case-insensitive matching request is made of a <b>mixed</b> sensitivity
file system, the behavior is generally the same as would be expected of a
purely case-insensitive file system. The difference is that a mixed sensitivity
file system might contain directories with multiple names that are unique
from a case-sensitive perspective, but not unique from the case-insensitive
perspective.</p>
<p>For example, a directory might contain files <tt>foo</tt>,
<tt>Foo</tt>, and <tt>FOO</tt>. If a request is made
to case-insensitively match any of the possible forms of <tt>foo</tt>,
(for example <tt>foo</tt>, <tt>FOO</tt>, <tt>FoO</tt>, <tt>fOo</tt>, and so on) one of the three existing files is chosen as the
match by the matching algorithm. Exactly which file the algorithm chooses
as a match is not guaranteed, but what is guaranteed is that the same file
is chosen as a match for any of the forms of <tt>foo</tt>. The
file chosen as a case-insensitive match for <tt>foo</tt>, <tt>FOO</tt>, <tt>foO</tt>, <tt>Foo</tt>, and so on,
is always the same, so long as the directory remains unchanged.</p>
<p>The <tt>utf8only</tt>, <tt>normalization</tt>, and <tt>casesensitivity</tt> properties are also new permissions that can be
assigned to non-privileged users by using ZFS delegated administration. For
more information, see <a href="chapter8.html#gfkco">Delegating ZFS Permissions</a>.</p>

<a name="gcfgv"></a>
<h4>The recordsize Property</h4>
<p>Specifies a suggested block size for files in the file system.</p>
<p>This property is designed solely for use with database workloads that
access files in fixed-size records. ZFS automatically adjust block sizes according
to internal algorithms optimized for typical access patterns. For databases
that create very large files but access the files in small random chunks,
these algorithms may be suboptimal. Specifying a <tt>recordsize</tt> greater
than or equal to the record size of the database can result in significant
performance gains. Use of this property for general purpose file systems is
strongly discouraged, and may adversely affect performance. The size specified
must be a power of two greater than or equal to 512 and less than or equal
to 128 Kbytes. Changing the file system's <tt>recordsize</tt> only
affects files created afterward. Existing files are unaffected.</p>
<p>This property can also be referred to by its shortened column name, <tt>recsize</tt>.</p>

<a name="gfwpk"></a>
<h4>The sharesmb Property</h4>
<p>This property enabled sharing of ZFS file systems with the Solaris CIFS
service, and identifies options to be used. </p>
<p>Because SMB shares requires a resource name, a unique resource name
is constructed from the dataset name. The constructed name is a copy of the
dataset name except that the characters in the dataset name, which would
be illegal in the resource name, are replaced with underscore (_) characters.
A pseudo property <tt><i>name</i></tt> is also supported
that allows you to replace the dataset name with a specific name. The specific
name is then used to replace the prefix dataset in the case of inheritance.</p>
<p>For example, if the dataset, <tt>data/home/john</tt>, is
set to <tt>name=john</tt>, then <tt> data/home/john</tt> has
a resource name of <tt>john</tt>. If a child dataset of <tt>data/home/john/backups</tt> exists, it has a resource name of <tt>john_backups</tt>.
When the <tt>sharesmb</tt> property is changed for a dataset, the
dataset and any children inheriting the property are re-shared with the new
options, only if the property was previously set to <tt>off</tt>,
or if they were shared before the property was changed. If the new property
is set to <tt>off</tt>, the file systems are unshared.</p>
<p>For examples of using the <tt>sharesmb</tt> property, see <a href="chapter5.html#gfwqv">Sharing ZFS Files in a Solaris CIFS Environment</a>.</p>

<a name="gcfhk"></a>
<h4>The volsize Property</h4>
<p>The logical size of the volume. By default, creating a volume establishes
a reservation for the same amount. Any changes to <tt>volsize</tt> are
reflected in an equivalent change to the reservation. These checks are used
to prevent unexpected behavior for users. A volume that contains less space
than it claims is available can result in undefined behavior or data corruption,
depending on how the volume is used. These effects can also occur when the
volume size is changed while it is in use, particularly when you shrink the
size. Extreme care should be used when adjusting the volume size.</p>
<p>Though not recommended, you can create a sparse volume by specifying
the <tt>s</tt> flag to <tt>zfs create -V</tt>, or by changing
the reservation once the volume has been created. A <b>sparse volume</b> is
defined as a volume where the reservation is not equal to the volume size.
For a sparse volume, changes to <tt>volsize</tt> are not reflected
in the reservation.</p>
<p>For more information about using volumes, see <a href="chapter9.html#gaypf">ZFS
Volumes</a>.</p>


<a name="gdrcw"></a>
<h3>ZFS User Properties</h3>
<p>In addition to the standard native properties, ZFS supports arbitrary
user properties. User properties have no effect on ZFS behavior, but you can
use them to annotate datasets with information that is meaningful in your
environment.</p>
<p>User property names must conform to the following characteristics:</p>
<ul>
<li>
<p>Contain a colon (':') character to distinguish them from native
properties.</p>

</li>
<li>
<p>Contain lowercase letters, numbers, and the following punctuation
characters: ':', + ,'.', '_'. </p>

</li>
<li>
<p>Maximum user property name is 256 characters.</p>

</li>
</ul>
<p>The expected convention is that the property name is divided into the
following two components but this namespace is not enforced by ZFS:</p>
<pre>
<tt><tt><i>module:property</i></tt></tt>
</pre>
<p>When making programmatic use of user properties, use a reversed DNS
domain name for the <tt><i>module</i></tt> component of property
names to reduce the chance that two independently-developed packages will
use the same property name for different purposes. Property names that begin
with "com.sun." are reserved for use by Sun Microsystems.</p>
<p>The values of user properties have the following characteristics:</p>
<ul>
<li>
<p>Arbitrary strings that are always inherited and are never
validated.</p>

</li>
<li>
<p>Maximum user property value is 1024 characters.</p>

</li>
</ul>
<p>For example:</p>
<pre>
<tt># <tt>zfs set dept:users=finance userpool/user1</tt>
# <tt>zfs set dept:users=general userpool/user2</tt>
# <tt>zfs set dept:users=itops userpool/user3</tt></tt>
</pre>
<p>All of the commands that operate on properties, such as <tt>zfs
list</tt>, <tt>zfs get</tt>, <tt>zfs set</tt>, and
so on, can be used to manipulate both native properties and user properties.</p>
<p>For example:</p>
<pre>
<tt><tt>zfs get -r dept:users userpool</tt>
NAME PROPERTY VALUE SOURCE
userpool dept:users all local
userpool/user1 dept:users finance local
userpool/user2 dept:users general local
userpool/user3 dept:users itops local</tt>
</pre>
<p>To clear a user property, use the <tt>zfs inherit</tt> command.
For example:</p>
<pre>
<tt># <tt>zfs inherit -r dept:users userpool</tt></tt>
</pre>
<p>If the property is not defined in any parent dataset, it is removed
entirely.</p>


<a name="gazsu"></a>
<h3>Querying ZFS File System Information</h3>
<p>The <tt>zfs list</tt> command provides an extensible mechanism
for viewing and querying dataset information. Both basic and complex queries
are explained in this section.</p>
<a name="gaztd"></a>
<h3>Listing Basic ZFS Information</h3>
<p>You can list basic dataset information by using the <tt>zfs list</tt> command
with no options. This command displays the names of all datasets on the system
including their <tt>used</tt>, <tt>available</tt>, <tt>referenced</tt>, and <tt>mountpoint</tt> properties. For
more information about these properties, see <a href="chapter5.html#gazss">Introducing
ZFS Properties</a>.</p>
<p>For example:</p>
<pre>
<tt># <tt>zfs list</tt>
NAME USED AVAIL REFER MOUNTPOINT
pool 476K 16.5G 21K /pool
pool/clone 18K 16.5G 18K /pool/clone
pool/home 296K 16.5G 19K /pool/home
pool/home/marks 277K 16.5G 277K /pool/home/marks
pool/home/marks@snap 0 - 277K -
pool/test 18K 16.5G 18K /test</tt>
</pre>
<p>You can also use this command to display specific datasets by providing
the dataset name on the command line. Additionally, use the <tt>r</tt> option
to recursively display all descendents of that dataset. For example:</p>
<pre>
<tt># <tt>zfs list -r pool/home/marks</tt>
NAME USED AVAIL REFER MOUNTPOINT
pool/home/marks 277K 16.5G 277K /pool/home/marks
pool/home/marks@snap 0 - 277K -</tt>
</pre>
<p>You use <tt>zfs list</tt> command with absolute pathnames
for datasets, snapshots, and volumes. For example:</p>
<pre>
<tt># <tt>zfs list /pool/home/marks</tt>
NAME USED AVAIL REFER MOUNTPOINT
pool/home/marks 277K 16.5G 277K /pool/home/marks</tt>
</pre>
<p>The following example shows how to display <tt>tank/home/chua</tt> and
all of its descendent datasets.</p>
<pre>
<tt># <tt>zfs list -r tank/home/chua</tt>
NAME USED AVAIL REFER MOUNTPOINT
tank/home/chua 26.0K 4.81G 10.0K /tank/home/chua
tank/home/chua/projects 16K 4.81G 9.0K /tank/home/chua/projects
tank/home/chua/projects/fs1 8K 4.81G 8K /tank/home/chua/projects/fs1
tank/home/chua/projects/fs2 8K 4.81G 8K /tank/home/chua/projects/fs2</tt>
</pre>
<p>For additional information about the <tt>zfs list</tt> command,
see zfs1M.</p>

<a name="gazsh"></a>
<h3>Creating Complex ZFS Queries</h3>
<p>The <tt>zfs list</tt> output can be customized by using of
the <tt>o</tt>, <tt>f</tt>, and <tt>H</tt> options.</p>
<p>You can customize property value output by using the <tt>o</tt> option
and a comma-separated list of desired properties. Supply any dataset property
as a valid value. For a list of all supported dataset properties, see <a href="chapter5.html#gazss">Introducing ZFS Properties</a>. In addition to the properties
defined there, the <tt>o</tt> option list can also contain the literal <tt>name</tt> to indicate that the output should include the name of the
dataset. </p>
<p>The following example uses <tt>zfs list</tt> to display the
dataset name, along with the <tt>sharenfs</tt> and <tt>mountpoint</tt> properties.</p>
<pre>
<tt># zfs list -o name,sharenfs,mountpoint
NAME SHARENFS MOUNTPOINT
tank off /tank
tank/home on /tank/home
tank/home/ahrens on /tank/home/ahrens
tank/home/bonwick on /tank/home/bonwick
tank/home/chua on /tank/home/chua
tank/home/eschrock on legacy
tank/home/moore on /tank/home/moore
tank/home/tabriz ro /tank/home/tabriz</tt>
</pre>
<p>You can use the <tt>t</tt> option to specify the types of datasets
to display. The valid types are described in the following table.</p>
<a name="gbaje"></a>
<h6>Types of ZFS Datasets</h6>
<table cellpadding="8" cellspacing="2" border="1">
<tr>
<th valign="" align="">
<p>Type</p>

</th><th valign="" align="">
<p>Description</p>

</th>
</tr>
<tr>
<td valign="" align="">
<p>
<tt>filesystem</tt>
</p>

</td><td valign="" align="">
<p>File systems and clones</p>

</td>
</tr>
<tr>
<td valign="" align="">
<p>
<tt>volume</tt>
</p>

</td><td valign="" align="">
<p>Volumes</p>

</td>
</tr>
<tr>
<td valign="" align="">
<p>
<tt>snapshot</tt>
</p>

</td><td valign="" align="">
<p>Snapshots</p>

</td>
</tr>
</table>
<p>The <tt>t</tt> options takes a comma-separated list of the types
of datasets to be displayed. The following example uses the <tt>t</tt> and <tt>o</tt> options simultaneously to show the name and <tt>used</tt> property
for all file systems:</p>
<pre>
<tt># <tt>zfs list -t filesystem -o name,used</tt>
NAME USED
pool 476K
pool/clone 18K
pool/home 296K
pool/home/marks 277K
pool/test 18K</tt>
</pre>
<p>You can use the <tt>H</tt> option to omit the <tt>zfs list</tt> header
from the generated output. With the <tt>H</tt> option, all white space
is output as tabs. This option can be useful when you need parseable output,
for example, when scripting. The following example shows the output generated
from using the <tt>zfs list</tt> command with the <tt>H</tt> option:</p>
<pre>
<tt># <tt>zfs list -H -o name</tt>
pool
pool/clone
pool/home
pool/home/marks
pool/home/marks@snap
pool/test</tt>
</pre>


<a name="gayns"></a>
<h3>Managing ZFS Properties</h3>
<p>Dataset properties are managed through the <tt>zfs</tt> command's <tt>set</tt>, <tt>inherit</tt>, and <tt>get</tt> subcommands.</p>
<ul>
<li>
<p>
<a href="chapter5.html#gazsp">Setting ZFS Properties</a>
</p>

</li>
<li>
<p>
<a href="chapter5.html#gazup">Inheriting ZFS Properties</a>
</p>

</li>
<li>
<p>
<a href="chapter5.html#gazuk">Querying ZFS Properties</a>
</p>

</li>
</ul>
<a name="gazsp"></a>
<h3>Setting ZFS Properties</h3>
<p>You can use the <tt>zfs set</tt> command to modify any settable
dataset property. Or, you can use the <tt>zfs create</tt> command
to set properties when the dataset is created. For a list of settable dataset
properties, see <a href="chapter5.html#gazsd">Settable ZFS Native Properties</a>.
The <tt>zfs set</tt> command takes a property/value sequence in
the format of <tt><i>property</i></tt>=<tt><i>value</i></tt> and
a dataset name.</p>
<p>The following example sets the <tt>atime</tt> property to <tt>off</tt> for <tt>tank/home</tt>. Only one property can be
set or modified during each <tt>zfs set</tt> invocation.</p>
<pre>
<tt># <tt>zfs set atime=off tank/home</tt></tt>
</pre>
<p>In addition, any file system property can be set when the file system
is created. For example:</p>
<pre>
<tt># <tt>zfs create -o atime=off tank/home</tt></tt>
</pre>
<p>You can specify numeric properties by using the following easy to understand
suffixes (in order of magnitude): <tt>BKMGTPEZ</tt>. Any of these
suffixes can be followed by an optional <tt>b</tt>, indicating bytes,
with the exception of the <tt>B</tt> suffix, which already indicates
bytes. The following four invocations of <tt>zfs set</tt> are equivalent
numeric expressions indicating that the <tt>quota</tt> property
be set to the value of 50 Gbytes on the <tt>tank/home/marks</tt> file
system:</p>
<pre>
<tt># <tt>zfs set quota=50G tank/home/marks</tt>
# <tt>zfs set quota=50g tank/home/marks</tt>
# <tt>zfs set quota=50GB tank/home/marks</tt>
# <tt>zfs set quota=50gb tank/home/marks</tt></tt>
</pre>
<p>Values of non-numeric properties are case-sensitive and must be lowercase,
with the exception of <tt>mountpoint</tt> and <tt>sharenfs</tt>.
The values of these properties can have mixed upper and lower case letters.</p>
<p>For more information about the <tt>zfs set</tt> command, see zfs1M.</p>

<a name="gazup"></a>
<h3>Inheriting ZFS Properties</h3>
<p>All settable properties, with the exception of quotas and reservations,
inherit their value from their parent, unless a quota or reservation is explicitly
set on the child. If no ancestor has an explicit value set for an inherited
property, the default value for the property is used. You can use the <tt>zfs
inherit</tt> command to clear a property setting, thus causing the setting
to be inherited from the parent.</p>
<p>The following example uses the <tt>zfs set</tt> command to
turn on compression for the <tt>tank/home/bonwick</tt> file system.
Then, <tt>zfs inherit</tt> is used to unset the <tt>compression</tt> property,
thus causing the property to inherit the default setting of <tt>off</tt>.
Because neither <tt>home</tt> nor <tt>tank</tt> have
the <tt>compression</tt> property set locally, the default value
is used. If both had compression on, the value set in the most immediate ancestor
would be used (<tt>home</tt> in this example).</p>
<pre>
<tt># <tt>zfs set compression=on tank/home/bonwick</tt>
# <tt>zfs get -r compression tank</tt>
NAME PROPERTY VALUE SOURCE
tank compression off default
tank/home compression off default
tank/home/bonwick compression on local
# <tt>zfs inherit compression tank/home/bonwick</tt>
# <tt>zfs get -r compression tank</tt>
NAME PROPERTY VALUE SOURCE
tank compression off default
tank/home compression off default
tank/home/bonwick compression off default</tt>
</pre>
<p>The <tt>inherit</tt> subcommand is applied recursively when
the <tt>r</tt> option is specified. In the following example, the
command causes the value for the <tt>compression</tt> property
to be inherited by <tt>tank/home</tt> and any descendents it might
have.</p>
<pre>
<tt># <tt>zfs inherit -r compression tank/home</tt></tt>
</pre>
<hr>
<p>
<b>Note - </b>
<p>Be aware that the use of the <tt>r</tt> option clears
the current property setting for all descendent datasets.</p>

</p>
<hr>
<p>For more information about the <tt>zfs</tt> command, see zfs1M.</p>

<a name="gazuk"></a>
<h3>Querying ZFS Properties</h3>
<p>The simplest way to query property values is by using the <tt>zfs
list</tt> command. For more information, see <a href="chapter5.html#gaztd">Listing
Basic ZFS Information</a>. However, for complicated queries and for scripting,
use the <tt>zfs get</tt> command to provide more detailed information
in a customized format.</p>
<p>You can use the <tt>zfs get</tt> command to retrieve any dataset
property. The following example shows how to retrieve a single property on
a dataset:</p>
<pre>
<tt># <tt>zfs get checksum tank/ws</tt>
NAME PROPERTY VALUE SOURCE
tank/ws checksum on default</tt>
</pre>
<p>The fourth column, <tt>SOURCE</tt>, indicates where this property
value has been set from. The following table defines the meaning of the possible
source values. </p>
<a name="gbavh"></a>
<h6>Possible SOURCE Values
(zfs get)</h6>
<table cellpadding="8" cellspacing="2" border="1">
<tr>
<th valign="" align="">
<p>Source Value</p>

</th><th valign="" align="">
<p>Description</p>

</th>
</tr>
<tr>
<td valign="" align="">
<p>
<tt>default</tt>
</p>

</td><td valign="" align="">
<p>This property was never explicitly set for this dataset or any of its
ancestors. The default value for this property is being used.</p>

</td>
</tr>
<tr>
<td valign="" align="">
<p>
<tt>inherited from</tt> <tt><i>dataset-name</i></tt>
</p>

</td><td valign="" align="">
<p>This property value is being inherited from the parent as specified
by <tt><i>dataset-name</i></tt>.</p>

</td>
</tr>
<tr>
<td valign="" align="">
<p>
<tt>local</tt>
</p>

</td><td valign="" align="">
<p>This property value was explicitly set for this dataset by using <tt>zfs
set</tt>.</p>

</td>
</tr>
<tr>
<td valign="" align="">
<p>
<tt>temporary</tt>
</p>

</td><td valign="" align="">
<p>This property value was set by using the <tt>zfs mount</tt> <tt>o</tt> option and is only valid for the lifetime of the mount. For more
information about temporary mount point properties, see <a href="chapter5.html#gamnt">Using Temporary Mount Properties</a>.</p>

</td>
</tr>
<tr>
<td valign="" align="">
<p>- (none)</p>

</td><td valign="" align="">
<p>This property is a read-only property. Its value is generated by ZFS.</p>

</td>
</tr>
</table>
<p>You can use the special keyword <tt>all</tt> to retrieve all
dataset properties. The following example uses the <tt>all</tt> keyword
to retrieve all existing dataset properties:</p>
<pre>
<tt># <tt>zfs get all tank</tt>
NAME PROPERTY VALUE SOURCE
tank type filesystem -
tank creation Wed Jan 23 9:57 2008 -
tank used 120K -
tank available 33.1G -
tank referenced 24.0K -
tank compressratio 1.00x -
tank mounted yes -
tank quota none default
tank reservation none default
tank recordsize 128K default
tank mountpoint /tank default
tank sharenfs off default
tank checksum on default
tank compression off default
tank atime on default
tank devices on default
tank exec on default
tank setuid on default
tank readonly off default
tank zoned off default
tank snapdir hidden default
tank aclmode groupmask default
tank aclinherit secure default
tank canmount on default
tank shareiscsi off default
tank xattr on default
tank copies 1 default
tank version 3 -
tank utf8only off -
tank normalization none -
tank casesensitivity sensitive -
tank vscan off default
tank nbmand off default
tank sharesmb off default
tank refquota none default
tank refreservation none default</tt>
</pre>
<p>The <tt>s</tt> option to <tt>zfs get</tt> enables
you to specify, by source value, the type of properties to display. This option
takes a comma-separated list indicating the desired source types. Only properties
with the specified source type are displayed. The valid source types are <tt>local</tt>, <tt>default</tt>, <tt>inherited</tt>, <tt>temporary</tt>, and <tt>none</tt>. The following example shows
all properties that have been locally set on <tt>pool</tt>.</p>
<pre>
<tt># <tt>zfs get -s local all pool</tt>
NAME PROPERTY VALUE SOURCE
pool compression on local</tt>
</pre>
<p>Any of the above options can be combined with the <tt>r</tt> option
to recursively display the specified properties on all children of the specified
dataset. In the following example, all temporary properties on all datasets
within <tt>tank</tt> are recursively displayed:</p>
<pre>
<tt># <tt>zfs get -r -s temporary all tank</tt>
NAME PROPERTY VALUE SOURCE
tank/home atime off temporary
tank/home/bonwick atime off temporary
tank/home/marks atime off temporary</tt>
</pre>
<p>A recent feature enables you to make queries with the <tt>zfs get</tt> command
without specifying a target file system, which means it operates on all pools
or file systems. For example:</p>
<pre>
<tt># <tt>zfs get -s local all</tt>
tank/home atime off local
tank/home/bonwick atime off local
tank/home/marks quota 50G local</tt>
</pre>
<p>For more information about the <tt>zfs get</tt> command, see zfs1M.</p>
<a name="gazum"></a>
<h4>Querying ZFS Properties for Scripting</h4>
<p>The <tt>zfs get</tt> command supports the <tt>H</tt> and <tt>o</tt> options, which are designed for scripting. The <tt>H</tt> option
indicates that any header information should be omitted and that all white
space should come in the form of tab. Uniform white space allows for easily
parseable data. You can use the <tt>o</tt> option to customize the
output. This option takes a comma-separated list of values to be output. All
properties defined in <a href="chapter5.html#gazss">Introducing ZFS Properties</a>,
along with the literals <tt>name</tt>, <tt>value</tt>, <tt>property</tt> and <tt>source</tt> can be supplied in the <tt>o</tt> list.</p>
<p>The following example shows how to retrieve a single value by using
the <tt>H</tt> and <tt>o</tt> options of <tt>zfs get</tt>.</p>
<pre>
<tt># <tt>zfs get -H -o value compression tank/home</tt>
on</tt>
</pre>
<p>The <tt>p</tt> option reports numeric values as their exact
values. For example, 1 Mbyte would be reported as 1000000. This option can
be used as follows:</p>
<pre>
<tt># <tt>zfs get -H -o value -p used tank/home</tt>
182983742</tt>
</pre>
<p>You can use the <tt>r</tt> option along with any of the above
options to recursively retrieve the requested values for all descendents.
The following example uses the <tt>r</tt>, <tt>o</tt>, and <tt>H</tt> options to retrieve the dataset name and the value of the <tt>used</tt> property for <tt>export/home</tt> and its descendents,
while omitting any header output:</p>
<pre>
<tt># <tt>zfs get -H -o name,value -r used export/home</tt>
export/home 5.57G
export/home/marks 1.43G
export/home/maybee 2.15G</tt>
</pre>



<a name="gaynd"></a>
<h3>Mounting and Sharing ZFS File Systems</h3>
<p>This section describes how mount points and shared file systems are
managed in ZFS.</p>
<ul>
<li>
<p>
<a href="chapter5.html#gaztn">Managing ZFS Mount Points</a>
</p>

</li>
<li>
<p>
<a href="chapter5.html#gamns">Mounting ZFS File Systems</a>
</p>

</li>
<li>
<p>
<a href="chapter5.html#gamnt">Using Temporary Mount Properties</a>
</p>

</li>
<li>
<p>
<a href="chapter5.html#gamnr">Unmounting ZFS File Systems</a>
</p>

</li>
<li>
<p>
<a href="chapter5.html#gamnd">Sharing and Unsharing ZFS File Systems</a>
</p>

</li>
</ul>
<a name="gaztn"></a>
<h3>Managing ZFS Mount Points</h3>
<p>By default, all ZFS file systems are mounted by ZFS at boot by using
SMF's <tt>svc://system/filesystem/local</tt> service. File systems
are mounted under <tt><i>/path</i></tt>, where <tt><i>path</i></tt> is
the name of the file system.</p>
<p>You can override the default mount point by setting the <tt>mountpoint</tt> property to a specific path by using the <tt>zfs set</tt> command.
ZFS automatically creates this mount point, if needed, and automatically mounts
this file system when the <tt>zfs mount -a</tt> command is invoked,
without requiring you to edit the <tt>/etc/vfstab</tt> file.</p>
<p>The <tt>mountpoint</tt> property is inherited. For example,
if <tt>pool/home</tt> has <tt>mountpoint</tt> set
to <tt>/export/stuff</tt>, then <tt>pool/home/user</tt> inherits <tt>/export/stuff/user</tt> for its <tt>mountpoint</tt> property.</p>
<p>The <tt>mountpoint</tt> property can be set to <tt>none</tt> to
prevent the file system from being mounted. In addition, the <tt>canmount</tt> property
is available for determining whether a file system can be mounted. For more
information about the <tt>canmount</tt> property, see <a href="chapter5.html#gdrcf">The canmount Property</a>.</p>
<p>If desired, file systems can also be explicitly managed through legacy
mount interfaces by setting the <tt>mountpoint</tt> property to <tt>legacy</tt> by using <tt>zfs set</tt>. Doing so prevents ZFS
from automatically mounting and managing this file system. Legacy tools including
the <tt>mount</tt> and <tt>umount</tt> commands, and the <tt>/etc/vfstab</tt> file must be used instead. For more information about
legacy mounts, see <a href="chapter5.html#gbaln">Legacy Mount Points</a>.</p>
<p>When changing mount point management strategies, the following behaviors
apply:</p>
<ul>
<li>
<p>Automatic mount point behavior</p>

</li>
<li>
<p>Legacy mount point behavior</p>

</li>
</ul>
<a name="gbala"></a>
<h4>Automatic Mount Points</h4>
<ul>
<li>
<p>When changing from <tt>legacy</tt> or <tt>none</tt>,
ZFS automatically mounts the file system.</p>

</li>
<li>
<p>If ZFS is currently managing the file system but it is currently
unmounted, and the <tt>mountpoint</tt> property is changed, the
file system remains unmounted.</p>

</li>
</ul>
<p>You can also set the default mount point for the root dataset at creation
time by using <tt>zpool create</tt>'s <tt>m</tt> option.
For more information about creating pools, see <a href="chapter4.html#gaynr">Creating
a ZFS Storage Pool</a>.</p>
<p>Any dataset whose <tt>mountpoint</tt> property is not <tt>legacy</tt> is managed by ZFS. In the following example, a dataset is
created whose mount point is automatically managed by ZFS.</p>
<pre>
<tt># <tt>zfs create pool/filesystem</tt>
# <tt>zfs get mountpoint pool/filesystem</tt>
NAME PROPERTY VALUE SOURCE
pool/filesystem mountpoint /pool/filesystem default
# <tt>zfs get mounted pool/filesystem</tt>
NAME PROPERTY VALUE SOURCE
pool/filesystem mounted yes -</tt>
</pre>
<p>You can also explicitly set the <tt>mountpoint</tt> property
as shown in the following example:</p>
<pre>
<tt># <tt>zfs set mountpoint=/mnt pool/filesystem</tt>
# <tt>zfs get mountpoint pool/filesystem</tt>
NAME PROPERTY VALUE SOURCE
pool/filesystem mountpoint /mnt local
# <tt>zfs get mounted pool/filesystem</tt>
NAME PROPERTY VALUE SOURCE
pool/filesystem mounted yes -</tt>
</pre>
<p>When the <tt>mountpoint</tt> property is changed, the file
system is automatically unmounted from the old mount point and remounted to
the new mount point. Mount point directories are created as needed. If ZFS
is unable to unmount a file system due to it being active, an error is reported
and a forced manual unmount is necessary.</p>

<a name="gbaln"></a>
<h4>Legacy Mount Points</h4>
<p>You can manage ZFS file systems with legacy tools by setting the <tt>mountpoint</tt> property to <tt>legacy</tt>. Legacy file
systems must be managed through the <tt>mount</tt> and <tt>umount</tt> commands
and the <tt>/etc/vfstab</tt> file. ZFS does not automatically
mount legacy file systems on boot, and the ZFS <tt>mount</tt> and <tt>umount</tt> command do not operate on datasets of this type. The following
examples show how to set up and manage a ZFS dataset in legacy mode:</p>
<pre>
<tt># <tt>zfs set mountpoint=legacy tank/home/eschrock</tt>
# <tt>mount -F zfs tank/home/eschrock /mnt</tt></tt>
</pre>
<p>In
addition, you must mount them by creating entries in the <tt>/etc/vfstab</tt> file.
Otherwise, the <tt>system/filesystem/local</tt> service enters
maintenance mode when the system boots.</p>
<p>To automatically mount a legacy file system on boot, you must add an
entry to the <tt>/etc/vfstab</tt> file. The following example
shows what the entry in the <tt>/etc/vfstab</tt> file might look
like:</p>
<pre>
<tt>#device device mount FS fsck mount mount
#to mount to fsck point type pass at boot options
#

tank/home/eschrock - /mnt zfs - yes - </tt>
</pre>
<p>Note that the <tt>device to fsck</tt> and <tt>fsck pass</tt> entries
are set to <tt>-</tt>. This syntax is because the <tt>fsck</tt> command
is not applicable to ZFS file systems. For more information regarding data
integrity and the lack of need for <tt>fsck</tt> in ZFS, see <a href="chapter.html#gaypi">Transactional Semantics</a>.</p>


<a name="gamns"></a>
<h3>Mounting ZFS File Systems</h3>
<p>ZFS automatically mounts file systems when file systems are created
or when the system boots. Use of the <tt>zfs mount</tt> command
is necessary only when changing mount options or explicitly mounting or unmounting
file systems.</p>
<p>The <tt>zfs mount</tt> command with no arguments shows all
currently mounted file systems that are managed by ZFS. Legacy managed mount
points are not displayed. For example:</p>
<pre>
<tt># <tt>zfs mount</tt>
tank /tank
tank/home /tank/home
tank/home/bonwick /tank/home/bonwick
tank/ws /tank/ws</tt>
</pre>
<p>You can use the <tt>a</tt> option to mount all ZFS managed file
systems. Legacy managed file systems are not mounted. For example:</p>
<pre>
<tt># <tt>zfs mount -a</tt></tt>
</pre>
<p>By default, ZFS does not allow mounting on top of a nonempty directory.
To force a mount on top of a nonempty directory, you must use the <tt>O</tt> option.
For example:</p>
<pre>
<tt># <tt>zfs mount tank/home/lalt</tt>
cannot mount '/export/home/lalt': directory is not empty
use legacy mountpoint to allow this behavior, or use the -O flag
# <tt>zfs mount -O tank/home/lalt</tt></tt>
</pre>
<p>Legacy mount points must be managed through legacy tools. An attempt
to use ZFS tools results in an error. For example:</p>
<pre>
<tt># <tt>zfs mount pool/home/billm</tt>
cannot mount 'pool/home/billm': legacy mountpoint
use mount(1M) to mount this filesystem
# <tt>mount -F zfs tank/home/billm</tt></tt>
</pre>
<p>When a file system is mounted, it uses a set of mount options based
on the property values associated with the dataset. The correlation between
properties and mount options is as follows:</p>
<dl>
<dt>Property</dt>
<dd>
<p>Mount Options</p>

</dd>
<dt>
<tt>devices</tt>
</dt>
<dd>
<p>
<tt>devices/nodevices</tt>
</p>

</dd>
<dt>
<tt>exec</tt>
</dt>
<dd>
<p>
<tt>exec/noexec</tt>
</p>

</dd>
<dt>
<tt>readonly</tt>
</dt>
<dd>
<p>
<tt>ro/rw</tt>
</p>

</dd>
<dt>
<tt>setuid</tt>
</dt>
<dd>
<p>
<tt>setuid/nosetuid</tt>
</p>

</dd>
</dl>
<p>The mount option <tt>nosuid</tt> is an alias for <tt>nodevices,nosetuid</tt>.</p>
<p>You
can use the NFSv4 mirror mount features to help you better manage NFS-mounted
ZFS home directories. For a description of mirror mounts, see <a href="chapter.html#gfwqw">ZFS and File System Mirror Mounts</a>.</p>

<a name="gamnt"></a>
<h3>Using Temporary Mount Properties</h3>
<p>If any of the above options are set explicitly by using the<tt>o</tt> option
with the <tt>zfs mount</tt> command, the associated property value
is temporarily overridden. These property values are reported as <tt>temporary</tt> by the <tt>zfs get</tt> command and revert back to their
original settings when the file system is unmounted. If a property value is
changed while the dataset is mounted, the change takes effect immediately,
overriding any temporary setting.</p>
<p>In the following example, the read-only mount option is temporarily
set on the <tt>tank/home/perrin</tt> file system:</p>
<pre>
<tt># <tt>zfs mount -o ro tank/home/perrin</tt></tt>
</pre>
<p>In this example, the file system is assumed to be unmounted. To temporarily
change a property on a file system that is currently mounted, you must use
the special <tt>remount</tt> option. In the following example, the <tt>atime</tt> property is temporarily changed to <tt>off</tt> for
a file system that is currently mounted:</p>
<pre>
<tt># <tt>zfs mount -o remount,noatime tank/home/perrin</tt>
# <tt>zfs get atime tank/home/perrin</tt>
NAME PROPERTY VALUE SOURCE
tank/home/perrin atime off temporary</tt>
</pre>
<p>For more information about the <tt>zfs mount</tt> command,
see zfs1M.</p>

<a name="gamnr"></a>
<h3>Unmounting ZFS File Systems</h3>
<p>You can unmount file systems by using the <tt>zfs unmount</tt> subcommand.
The <tt>unmount</tt> command can take either the mount point or
the file system name as arguments.</p>
<p>In the following example, a file system is unmounted by file system
name:</p>
<pre>
<tt># <tt>zfs unmount tank/home/tabriz</tt></tt>
</pre>
<p>In the following example, the file system is unmounted by mount point:</p>
<pre>
<tt># <tt>zfs unmount /export/home/tabriz</tt></tt>
</pre>
<p>The <tt>unmount</tt> command fails if the file system is active
or busy. To forceably unmount a file system, you can use the <tt>f</tt> option.
Be cautious when forceably unmounting a file system, if its contents are actively
being used. Unpredictable application behavior can result.</p>
<pre>
<tt># <tt>zfs unmount tank/home/eschrock</tt>
cannot unmount '/export/home/eschrock': Device busy
# <tt>zfs unmount -f tank/home/eschrock</tt></tt>
</pre>
<p>To provide for backwards compatibility, the legacy <tt>umount</tt> command
can be used to unmount ZFS file systems. For example:</p>
<pre>
<tt># <tt>umount /export/home/bob</tt></tt>
</pre>
<p>For more information about the <tt>zfs umount</tt> command,
see zfs1M.</p>

<a name="gamnd"></a>
<h3>Sharing and Unsharing ZFS File Systems</h3>
<p>Similar to mount points, ZFS can automatically share file systems by
using the <tt>sharenfs</tt> property. Using this method, you do
not have to modify the <tt>/etc/dfs/dfstab</tt> file when a new
file system is added. The <tt>sharenfs</tt> property is a comma-separated
list of options to pass to the <tt>share</tt> command. The special
value <tt>on</tt> is an alias for the default share options, which
are <tt>read/write</tt> permissions for anyone. The special value <tt>off</tt> indicates that the file system is not managed by ZFS and can
be shared through traditional means, such as the <tt>/etc/dfs/dfstab</tt> file.
All file systems whose <tt>sharenfs</tt> property is not <tt>off</tt> are shared during boot.</p>
<a name="gbdxz"></a>
<h4>Controlling Share Semantics</h4>
<p>By default, all file systems are unshared. To share a new file system,
use <tt>zfs set</tt> syntax similar to the following:</p>
<pre>
<tt># <tt>zfs set sharenfs=on tank/home/eschrock</tt></tt>
</pre>
<p>The property is inherited, and file systems are automatically shared
on creation if their inherited property is not <tt>off</tt>. For
example:</p>
<pre>
<tt># <tt>zfs set sharenfs=on tank/home</tt>
# <tt>zfs create tank/home/bricker</tt>
# <tt>zfs create tank/home/tabriz</tt>
# <tt>zfs set sharenfs=ro tank/home/tabriz</tt></tt>
</pre>
<p>Both <tt>tank/home/bricker</tt> and <tt>tank/home/tabriz</tt> are
initially shared writable because they inherit the <tt>sharenfs</tt> property
from <tt>tank/home</tt>. Once the property is set to <tt>ro</tt> (readonly), <tt>tank/home/tabriz</tt> is shared read-only regardless of the <tt>sharenfs</tt> property that is set for <tt>tank/home</tt>.</p>

<a name="gbdze"></a>
<h4>Unsharing ZFS File Systems</h4>
<p>While most file systems are automatically shared and unshared during
boot, creation, and destruction, file systems sometimes need to be explicitly
unshared. To do so, use the <tt>zfs unshare</tt> command. For example:</p>
<pre>
<tt># <tt>zfs unshare tank/home/tabriz</tt></tt>
</pre>
<p>This command unshares the <tt>tank/home/tabriz</tt> file
system. To unshare all ZFS file systems on the system, you need to use the <tt>a</tt> option.</p>
<pre>
<tt># <tt>zfs unshare -a</tt></tt>
</pre>

<a name="gbdxw"></a>
<h4>Sharing ZFS File Systems</h4>
<p>Most of the time the automatic behavior of ZFS, sharing on boot and
creation, is sufficient for normal operation. If, for some reason, you unshare
a file system, you can share it again by using the <tt>zfs share</tt> command.
For example:</p>
<pre>
<tt># <tt>zfs share tank/home/tabriz</tt></tt>
</pre>
<p>You can also share all ZFS file systems on the system by using the <tt>a</tt> option.</p>
<pre>
<tt># <tt>zfs share -a</tt></tt>
</pre>

<a name="gbdxq"></a>
<h4>Legacy Share Behavior</h4>
<p>If the <tt>sharenfs</tt> property is <tt>off</tt>,
then ZFS does not attempt to share or unshare the file system at any time.
This setting enables you to administer through traditional means such as the <tt>/etc/dfs/dfstab</tt> file.</p>
<p>Unlike the traditional <tt>mount</tt> command, the traditional <tt>share</tt> and <tt>unshare</tt> commands can still function
on ZFS file systems. As a result, you can manually share a file system with
options that are different from the settings of the <tt>sharenfs</tt> property.
This administrative model is discouraged. Choose to either manage NFS shares
completely through ZFS or completely through the <tt>/etc/dfs/dfstab</tt> file.
The ZFS administrative model is designed to be simpler and less work than
the traditional model. However, in some cases, you might still want to control
file system sharing behavior through the familiar model.</p>


<a name="gfwqv"></a>
<h3>Sharing
ZFS Files in a Solaris CIFS Environment</h3>
<p>The <tt>sharesmb</tt> property is provided to share ZFS files
by using the Solaris CIFS software product. When this property is set on a
ZFS file system, these shares are visible to CIFS client systems. For more
information about using the CIFS software product, see the System
Administration Guide: Windows Interoperability.</p>
<p>For a detailed description of the <tt>sharesmb</tt> property,
see <a href="chapter5.html#gfwpk">The sharesmb Property</a>.</p>
<a name="gfwqk"></a>
<p>
<b>Example&mdash;Sharing ZFS File Systems (sharesmb)</b>
</p>
<h4>Example&mdash;Sharing ZFS File Systems (sharesmb)</h4>
<p>In this example, a ZFS file system <tt>sandbox/fs1</tt> is
created and shared with the <tt>sharesmb</tt> property. If necessary,
enable the SMB services.</p>
<pre>
<tt># svcadm enable -r smb/server
svcadm: svc:/milestone/network depends on svc:/network/physical, which has multiple instances.
# svcs | grep smb
online 10:47:15 svc:/network/smb/server:default</tt>
</pre>
<pre>
<tt># <tt>zpool create sandbox mirror c0t2d0 c0t4d0</tt>
# <tt>zfs create sandbox/fs1</tt>
# <tt>zfs set sharesmb=on sandbox/fs1</tt></tt>
</pre>
<p>The <tt>sharesmb</tt> property is set for <tt>sandbox/fs1</tt> and
its descendents.</p>
<p>Verify that the file system was shared. For example:</p>
<pre>
<tt># <tt>sharemgr show -vp</tt>
default nfs=()
zfs nfs=()
zfs/sandbox/fs1 smb=()
sandbox_fs1=/sandbox/fs1</tt>
</pre>
<p>A default SMB resource name, <tt>sandbox_fs1</tt>, is assigned
automatically.</p>
<p>In this example, another file system is created, <tt>sandbox/fs2</tt>,
and shared with a resource name, <tt>myshare</tt>.</p>
<pre>
<tt># <tt>zfs create sandbox/fs2</tt>
# <tt>zfs set sharesmb=name=myshare sandbox/fs2</tt>
# <tt>sharemgr show -vp</tt>
default nfs=()
zfs nfs=()
zfs/sandbox/fs1 smb=()
sandbox_fs1=/sandbox/fs1
zfs/sandbox/fs2 smb=()
myshare=/sandbox/fs2</tt>
</pre>
<p>The <tt>sandbox/fs2/fs2_sub1</tt> file system is created
and is automatically shared. The inherited resource name is <tt>myshare_fs2_sub1</tt>.</p>
<pre>
<tt># <tt>zfs create sandbox/fs2/fs2_sub1</tt>
# <tt>sharemgr show -vp</tt>
default nfs=()
zfs nfs=()
zfs/sandbox/fs1 smb=()
sandbox_fs1=/sandbox/fs1
zfs/sandbox/fs2 smb=()
myshare=/sandbox/fs2
myshare_fs2_sub1=/sandbox/fs2/fs2_sub1</tt>
</pre>
<p>Disable SMB sharing for <tt>sandbox/fs2</tt> and its descendents.</p>
<pre>
<tt># <tt>zfs set sharesmb=off sandbox/fs2</tt>
# <tt>sharemgr show -vp</tt>
default nfs=()
zfs nfs=()
zfs/sandbox/fs1 smb=()
sandbox_fs1=/sandbox/fs1</tt>
</pre>

<p>In this example, the <tt>sharesmb</tt> property is set on
the pool's top-level file system. The descendent file systems are automatically
shared.</p>
<pre>
<tt># <tt>zpool create sandbox mirror c0t2d0 c0t4d0</tt>
# <tt>zfs set sharesmb=on sandbox</tt>
# <tt>zfs create sandbox/fs1</tt>
# <tt>zfs create sandbox/fs2</tt></tt>
</pre>
<p>The top-level file system has a resource name of <tt>sandbox</tt>,
but the descendents have their dataset name appended to the resource name.</p>
<pre>
<tt># <tt>sharemgr show -vp</tt>
default nfs=()
zfs nfs=()
zfs/sandbox smb=()
sandbox=/sandbox
sandbox_fs1=/sandbox/fs1 smb=()
sandbox_fs2=/sandbox/fs2 smb=()</tt>
</pre>


<a name="gazvb"></a>
<h3>ZFS Quotas and Reservations</h3>
<p>ZFS supports quotas and reservations at the file system level. You can
use the <tt>quota</tt> property to set a limit on the amount of
space a file system can use. In addition, you can use the <tt>reservation</tt> property
to guarantee that some amount of space is available to a file system. Both
properties apply to the dataset they are set on and all descendents of that
dataset.</p>
<p>That is, if a quota is set on the <tt>tank/home</tt> dataset,
the total amount of space used by <tt>tank/home</tt> <b>and
all of its descendents</b> cannot exceed the quota. Similarly, if <tt>tank/home</tt> is given a reservation, <tt>tank/home</tt> <b>and all of its descendents</b> draw from that reservation. The amount
of space used by a dataset and all of its descendents is reported by the <tt>used</tt> property.</p>
<p>In addition to the <tt>quota</tt> and <tt>reservation</tt> property, the <tt>refquota</tt> and <tt>refreservation</tt> properties are available
to manage file system space without accounting for space consumed by descendents,
such as snapshots and clones.</p>
<p>Consider the following points to determine
which quota and reservations features might better manage your file systems:</p>
<ul>
<li>
<p>The <tt>quota</tt> and <tt>reservation</tt> properties
are convenient for managing space consumed by datasets.</p>

</li>
<li>
<p>The <tt>refquota</tt> and <tt>refreservation</tt> properties
are appropriate for managing space consumed by datasets and snapshots. </p>

</li>
<li>
<p>Setting <tt>refquota</tt> or <tt>refreservation</tt> higher
than quota or reservation have no effect. If you set the <tt>quota</tt> or <tt>refquota</tt> properties, operations that try to exceed either value
fail. It is possible to a exceed a <tt>quota</tt> that is greater
than <tt>refquota</tt>. If some snapshot blocks are dirtied, you
might actually exceed the <tt>quota</tt> before you exceed the <tt>refquota</tt>.</p>

</li>
</ul>
<p>For more information, see the examples below.</p>
<a name="gazud"></a>
<h3>Setting Quotas on ZFS File Systems</h3>
<p>ZFS quotas can be set and displayed by using the <tt>zfs set</tt> and <tt>zfs get</tt> commands. In the following example, a quota of 10 Gbytes
is set on <tt>tank/home/bonwick</tt>.</p>
<pre>
<tt># <tt>zfs set quota=10G tank/home/bonwick</tt>
# <tt>zfs get quota tank/home/bonwick</tt>
NAME PROPERTY VALUE SOURCE
tank/home/bonwick quota 10.0G local</tt>
</pre>
<p>ZFS quotas also impact the output of the <tt>zfs list</tt> and <tt>df</tt> commands. For example:</p>
<pre>
<tt># <tt>zfs list</tt>
NAME USED AVAIL REFER MOUNTPOINT
tank/home 16.5K 33.5G 8.50K /export/home
tank/home/bonwick 15.0K 10.0G 8.50K /export/home/bonwick
tank/home/bonwick/ws 6.50K 10.0G 8.50K /export/home/bonwick/ws
# <tt>df -h /export/home/bonwick</tt>
Filesystem size used avail capacity Mounted on
tank/home/bonwick 10G 8K 10G 1% /export/home/bonwick</tt>
</pre>
<p>Note that although <tt>tank/home</tt> has 33.5 Gbytes of
space available, <tt>tank/home/bonwick</tt> and <tt>tank/home/bonwick/ws</tt> only have 10 Gbytes of space available, due to the quota on <tt>tank/home/bonwick</tt>.</p>
<p>You cannot set a quota to an amount less than is currently being used
by a dataset. For example:</p>
<pre>
<tt># <tt>zfs set quota=10K tank/home/bonwick</tt>
cannot set quota for 'tank/home/bonwick': size is less than current used or
reserved space</tt>
</pre>
<p>You can set a <tt>refquota</tt> on a dataset that limits the amount of space that the dataset
can consume. This hard limit does not include space that is consumed by snapshots
and clones. For example:</p>
<pre>
<tt># <tt>zfs set refquota=10g students/studentA</tt>
# <tt>zfs list</tt>
NAME USED AVAIL REFER MOUNTPOINT
profs 106K 33.2G 18K /profs
students 57.7M 33.2G 19K /students
students/studentA 57.5M 9.94G 57.5M /students/studentA
# <tt>zfs snapshot students/studentA@today</tt>
# <tt>zfs list</tt>
NAME USED AVAIL REFER MOUNTPOINT
profs 106K 33.2G 18K /profs
students 57.7M 33.2G 19K /students
students/studentA 57.5M 9.94G 57.5M /students/studentA
students/studentA@today 0 - 57.5M -</tt>
</pre>
<p>For additional
convenience, you can set another quota on a dataset to help manage the space
that is consumed by snapshots. For example:</p>
<pre>
<tt># <tt>zfs set quota=20g students/studentA</tt>
# <tt>zfs list</tt>
NAME USED AVAIL REFER MOUNTPOINT
profs 106K 33.2G 18K /profs
students 57.7M 33.2G 19K /students
students/studentA 57.5M 9.94G 57.5M /students/studentA
students/studentA@today 0 - 57.5M -</tt>
</pre>
<p>In this scenario, <tt>studentA</tt> can bump into the refquota (10 Gbytes) hard limit and remove files
to recover even if snapshots exist.</p>
<p>In the above example, the
smaller of the two quotas (10 Gbytes versus 20 Gbytes) is displayed in the <tt>zfs list</tt> output. To see the value of both quotas, use the <tt>zfs
get</tt> command. For example:</p>
<pre>
<tt># <tt>zfs get refquota,quota students/studentA</tt>
NAME PROPERTY VALUE SOURCE
students/studentA refquota 10G local
students/studentA quota 20G local</tt>
</pre>

<a name="gbdbb"></a>
<h3>Setting Reservations on ZFS File Systems</h3>
<p>A ZFS <b>reservation</b> is an allocation of space from
the pool that is guaranteed to be available to a dataset. As such, you cannot
reserve space for a dataset if that space is not currently available in the
pool. The total amount of all outstanding unconsumed reservations cannot exceed
the amount of unused space in the pool. ZFS reservations can be set and displayed
by using the <tt>zfs set</tt> and <tt>zfs get</tt> commands.
For example:</p>
<pre>
<tt># <tt>zfs set reservation=5G tank/home/moore</tt>
# <tt>zfs get reservation tank/home/moore</tt>
NAME PROPERTY VALUE SOURCE
tank/home/moore reservation 5.00G local</tt>
</pre>
<p>ZFS reservations can affect the output of the <tt>zfs list</tt> command.
For example:</p>
<pre>
<tt># <tt>zfs list</tt>
NAME USED AVAIL REFER MOUNTPOINT
tank/home 5.00G 33.5G 8.50K /export/home
tank/home/moore 15.0K 10.0G 8.50K /export/home/moore</tt>
</pre>
<p>Note that <tt>tank/home</tt> is using 5 Gbytes of space,
although the total amount of space referred to by <tt>tank/home</tt> and
its descendents is much less than 5 Gbytes. The used space reflects the space
reserved for <tt>tank/home/moore</tt>. Reservations are considered
in the used space of the parent dataset and do count against its quota, reservation,
or both.</p>
<pre>
<tt># <tt>zfs set quota=5G pool/filesystem</tt>
# <tt>zfs set reservation=10G pool/filesystem/user1</tt>
cannot set reservation for 'pool/filesystem/user1': size is greater than
available space</tt>
</pre>
<p>A dataset can use more space than its reservation, as long as space
is available in the pool that is unreserved and the dataset's current usage
is below its quota. A dataset cannot consume space that has been reserved
for another dataset.</p>
<p>Reservations are not cumulative. That is, a second invocation of <tt>zfs
set</tt> to set a reservation does not add its reservation to the existing
reservation. Rather, the second reservation replaces the first reservation.</p>
<pre>
<tt># <tt>zfs set reservation=10G tank/home/moore</tt>
# <tt>zfs set reservation=5G tank/home/moore</tt>
# <tt>zfs get reservation tank/home/moore</tt>
NAME PROPERTY VALUE SOURCE
tank/home/moore reservation 5.00G local</tt>
</pre>
<p>You
can set a <tt>refreservation</tt> to guarantee space for a dataset
that does not include space consumed by snapshots and clones. The <tt>refreservation</tt> reservation is accounted for in the parent datasets' space used,
and counts against the parent datasets' quotas and reservations. For example:</p>
<pre>
<tt># <tt>zfs set refreservation=10g profs/prof1</tt>
# <tt>zfs list</tt>
NAME USED AVAIL REFER MOUNTPOINT
profs 10.0G 23.2G 19K /profs
profs/prof1 10G 33.2G 18K /profs/prof1</tt>
</pre>
<p>You
can also set a reservation on the same dataset to guarantee dataset space
and snapshot space. For example:</p>
<pre>
<tt># <tt>zfs set reservation=20g profs/prof1</tt>
# <tt>zfs list</tt>
NAME USED AVAIL REFER MOUNTPOINT
profs 20.0G 13.2G 19K /profs
profs/prof1 10G 33.2G 18K /profs/prof1</tt>
</pre>
<p>Regular
reservations are accounted for in the parent's used space.</p>
<p>In
the above example, the smaller of the two quotas (10 Gbytes versus 20 Gbytes)
is displayed in the <tt>zfs list</tt> output. To see the value of
both quotas, use the <tt>zfs get</tt> command. For example:</p>
<pre>
<tt># <tt>zfs get reservation,refreserv profs/prof1</tt>
NAME PROPERTY VALUE SOURCE
profs/prof1 reservation 20G local
profs/prof1 refreservation 10G local</tt>
</pre>
<p>If <tt>refreservation</tt> is set, a snapshot is only allowed if enough free pool space exists
outside of this reservation to accommodate the current number of <b>referenced</b> bytes in the dataset.</p>



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