How to Split a Root Mirrored With Solaris Volume Manager Prior to Updating Software

1. 

   May 18, 2009

   FuuBar says:

   How about this alternativ from bullet 3 less reboots both before and after. 3. ...

   How about this alternativ from bullet 3 less reboots both before and after.

   3. Fsck & Mount the detached disk (d12 disk c0t3d0s0 in this example):

   root@patchtest-x4200-2 # fsck -f /dev/dsk/c0t3d0s0
   root@patchtest-x4200-2 # mount /dev/dsk/c0t3d0s0 /mnt

   4. Revert to booting off the physical device on the detached disk (d12 disk c0t3d0s0 in this example):

   root@patchtest-x4200-2 # metaroot -R /mnt c0t3d0s0

   5. Verify that vfstab is now correct:

   root@patchtest-x4200-2 # grep c0t3d0s0 /mnt/etc/vfstab
   /dev/dsk/c0t3d0s0 /dev/rdsk/ / ufs 1 no -
   root@patchtest-x4200-2 # grep d10 /etc/vfstab
   root@patchtest-x4200-2 #

   6. Unmount c0t3d0s0 and perform any software maintenance steps.

   root@patchtest-x4200-2 # umount /mnt

   • Permalink

2. 

   May 19, 2009

   CCSUNGRP says:

   Hi All, However, the '/var', '/opt' & '/usr' directory's if they are on sep...

   Hi All,

   However, the '/var', '/opt' & '/usr' directory's if they are on separate partition's ( metadevice) ?

   Thanks & Regards

   • Permalink

3. 

   May 19, 2009

   Mickey_N says:

   Great article, but I'm missing instructions for reverting back to the untouched ...

   Great article, but I'm missing instructions for reverting back to the untouched mirror in case the upgrade fails. This seems to be the most challenging part of the operation.

   Also I have been struggling with this on an X4150 and got in to a bunch of unexpected issues due to re-addressing of disks, it seems as if the disk which is first in the boot sequence will always be target 0

   /Mikael

   • Permalink

4. 

   May 22, 2009

   eoconnor says:

   Hi So if you say /usr /var seperate then once you have followed the instructions...

   Hi
   So if you say /usr /var seperate then once you have followed the instructions in the doc for splitting root, and before rebooting run
   root@oyster # df -k /usr
   Filesystem kbytes used avail capacity Mounted on
   /dev/md/dsk/d30 5040814 3344800 1645606 68% /usr
   root@oyster # metastat -p d30
   d30 -m d31 d32 1
   d31 1 1 c0t1d0s5
   d32 1 1 c0t0d0s5
   root@oyster #
   root@oyster # metadetach d30 d32
   d30: submirror d32 is detached
   root@oyster #

   So now edit /etc/vfstab to enable /usr to be mounted off c0t1d0s5
   #/dev/md/dsk/d30 /dev/md/rdsk/d30 /usr ufs 1 no
   -
   /dev/dsk/c0t1d0s5 /dev/rdsk/c0t1d0s5 /ufs ufs 1 no
   ( best to just comment out original entries for now, as you'll need them later to reattach mirrors)
   Do same for say /opt etc.

   if swap is mirrored and you want to break swap mirror

   root@oyster # swap -l
   swapfile dev swaplo blocks free
   /dev/md/dsk/d40 85,40 16 2048272 2048272
   root@oyster # metastat -p d40
   d40 -m d41 d42 1
   d41 1 1 c0t2d0s3
   d42 1 1 c0t3d0s3
   root@oyster #

   root@oyster # metadetach d40 d42
   d40: submirror d42 is detached
   root@oyster

   then edit /etc/vfstab and modify to assign swap of one half of the mirror
   /dev/dsk/c0t2d0s3 - - swap - no -

   Then once /etc/vfstab is correct, reboot at that stage, and system will now boot with /, /usr etc mounted of the underlying disks.

   To reattach, run metaroot d10 and edit /etc/vfstab to mount the metadevices ( the original entries that existed ), then reboot
   and reattach the submirrors via
   #metattach d10 d12
   #metattach d30 d32
   and so on to reattach all the sub disks to their mirrors.

   metastat should then show all the mirrors and sub disks.

   ------

   For systems such as x4150 the boot disk is determined from boot priority in BIOS, so on x86 based systems it's important to consider that the disk that is listed first in the BIOS boot priority is where the system will look first for a grub menu, and then proceed to the second entry if none is found and so on.

   ------

   So if say you do boot of an underlying disk and the software update/upgrade fails, rendering the system unbootable, the options are to
   1. boot off failsafe
   ok> boot -F failsafe in SPARC u6 and beyond
   or select failsafe entry from grub on boot if x86
   2. Boot of network or cd|dvd etc

   Then once that has been accomplished you will need to access the metadevices ( follow as far as step 5 in "How to Mount a Solaris Volume Manager Mirror While Booted From Media" section in this doc.

   then
   say you had split the root mirror and it looked like the following after the split

   1. metastat -p d10
      d10 -m d11 1
      d11 1 1 c0t2d0s0
      #

   and d12, the detached half of the mirror was c0t3d0s0, and you now wanted to boot of that and probably recreate the mirror until figuring out the problem, you could do

   #metaclear d10 ( gets rid of the mirror )
   reinitialise the subdisks and mirror
   #metainit d11 1 1 c0t2d0s0

   #metainit d10 -m d12

   now you have

   1. metastat -p d10
      d10 -m d12 1
      d12 1 1 c0t3d0s0
      #

   Now mount /dev/dsk/c0t3d0s0 on /a and edit /a/etc/vfstab to boot of c0t3d0s0
   /dev/dsk/c0t3d0s0 /dev/rdsk/c0t3d0s0 / ufs 1 no -

   Also make sure that if /var and /usr etc are seperate mirrors devices, that you take care to boot of the unpatched side

   check /a/etc/system and comment out rootdev:/pseudo/md entry if it exists.

   then need to modify the eeprom variables to boot of c0t3d0s0
   so
   root@oyster # ls -l /dev/dsk/c0t3d0s0
   lrwxrwxrwx 1 root root 43 May 21 11:42 /dev/dsk/c0t3d0s0 -> ../../devices/pci@1c,600000/scsi@2/sd@3,0:a

   so we need to boot of
   /pci@1c,600000/scsi@2/disk@3,0:a ( note replace major name, sd in this case with disk )

   so need to set the following for instance in eeprom

   something like
   root@oyster # eeprom "nvramrc=devalias disk /pci@1c,600000/scsi@2/disk@2,0:a disk1 /pci@1c,600000/scsi@2/disk@3,0:a"
   root@oyster # eeprom "boot-device=disk1 disk net"

   This should then boot of disk1 /pci@1c,600000/scsi@2/sd@3,0:a otherwise known as c0t3d0s0

   after the reboot you should then be able to run
   #metaroot d10
   #metattach d10 d11

   and the d12 ( pre updating software disk ) will sync to d11.

   I would also recommend running fsck before booting of the underlying disk as in:

   #/usr/sbin/fsck -F ufs -m /dev/rdsk/c0t3d0s0
   this will run a sanity check and tell you if all is ok, if not then you obviously have problems and need to run
   /usr/sbin/fsck -F ufs -o p /dev/rdsk/c0t3d0s0
   at a minimum to repair the ufs metadata.

   Enda

   • Permalink

Sign up or Log in to add a comment or watch this page.