How to Enable the SRP Target Service

Service Management Facility for SRP Target

The COMSTAR port provider for the SCSI RDMA Protocol (the COMSTAR SRP Target) is managed by the System Management Facility. See the smf(5)man page. The SRP target service uses the Fault Management Resource Identifier of svc:/system/ibsrp/target:default, which can be abbreviated to ibsrp/target.

To enable the SRP target:

svcadm enable ibsrp/target

The SRP target service is dependent on the STMF service. To enable SRP along with all of its dependent services:

svcadm enable -r ibsrp/target

To get detailed status on the SRP service:

# svcs -vx ibsrp/target
# svcs -l ibsrp/target

One SCSI Target per InfiniBand HCA

The COMSTAR SRP target uses a simple model in which each supported InfiniBand Host Channel Adapter (HCA) is registered as a SCSI target. The SCSI target is a virtual object that contains a task router and acts as a the connection between the SCSI transport (in this case, SRP) and the SCSI back end (STMF and SBD).

An HCA can contain multiple physical ports. The same SCSI target is shared between all the ports of an HCA. The SCSI target representing the HCA is automatically available for incoming connections via all the active ports of that HCA.

SRP Target eui Identifier

In the IB architecture, each Host Channel Adapter (HCA) and each port is assigned a 64-bit GUID by the manufacturer. The COMSTAR SCSI target created for each HCA is given a name corresponding to the GUID of that HCA: eui.HCA-GUID. For example, if the target system includes a supported IB HCA with an HCA GUID of 0003BA0001002E48, then a SCSI target will be created using the name eui.0003BA0001002E48. The string eui stands for Extended Unique Identifier and names a class of GUIDs that is used in both the SCSI and IB Standards.

SRP Initiator eui Identifier

Similarly, SRP uses a 64-bit initiator GUID to identify the initiator system. The choice of which GUID to use is up to the SRP initiator implementation. Many initiators use the GUID of the HCA that is being used for the outgoing connection. An initiator using the GUID of 0003BA0001002EA5 will be known to COMSTAR as eui.0003BA0001002EA5.

Using COMSTAR Views with SRP

The COMSTAR View facility may be used to create target-groups and host-groups that restrict and configure which storage logical units can be accessed through each SCSI target or initiator as described in How to Make SCSI Logical Units Available. The eui identifier of the SRP initiator would be added to a host group. The eui identifer of the SRP SCSI Target would be added to a target group. The View Entries for each logical unit then determine the particular set of logical units that each initiator will see.

How to Verify SRP Target Status

Use the stmfadm list-target command to verify the presence in the system of an expected SRP SCSI target.

# stmfadm list-target -v
Target: eui.0003BA0001002E48
    Operational Status: Online
    Provider Name     : srpt
    Alias             : -
    Sessions          : 0

An SRP initiator with GUID 0003BA0001002EA5 then establishes an SRP connection.

# stmfadm list-target -v
Target: eui.0003BA0001002E48
    Operational Status: Online
    Provider Name     : srpt
    Alias             : -
    Sessions          : 1
        Initiator: eui.0003BA0001002EA5
            Alias: 4a2e000100ba0300:0003ba0001002ea5
            Logged in since: Tue Mar 31 20:23:52 2009

Where to Go Next

• How to Configure an SRP Initiator