2 Replies Latest reply: Jan 22, 2013 10:19 AM by bigdelboy RSS

    Mirror Mirror

    982087
      I have inherited a Sparc server running S10U8. I note that slice 4 is mirrored.

      Metastat shows:
      d40: Mirror
      Submirror 0: d41
      State: Okay
      Submirror 1: d42
      State: Okay
      Pass: 1
      Read option: roundrobin (default)
      Write option: parallel (default)
      Size: 71689920 blocks (34 GB)

      d41: Submirror of d40
      State: Okay
      Size: 71689920 blocks (34 GB)
      Stripe 0:
      Device Start Block Dbase State Reloc Hot Spare
      c1t0d0s4 0 No Okay Yes


      d42: Submirror of d40
      State: Okay
      Size: 71689920 blocks (34 GB)
      Stripe 0:
      Device Start Block Dbase State Reloc Hot Spare
      c1t1d0s4 0 No Okay Yes


      Yet vfstab shows that slice 4 is mounted as:
      /dev/dsk/c1t0d0s4 /dev/rdsk/c1t0d0s4 /apps ufs 2 yes
      -

      and df -h shows:
      /dev/dsk/c1t0d0s4 34G 22G 12G 66% /apps

      So tell me, is slice 4 being mirrored or not? Is the "fix" as easy as just changing vfstab to /dev/md/dsk/d40?
        • 1. Re: Mirror Mirror
          bobthesungeek76036
          My fix for this would be to remove the d42 mirror, change the vfstab to mount d40, remount /apps using the d40 metadevice, add the d42 mirror. Commands would look something like this:

          <pre>
          metadetach d40 d42
          <i>edit /etc/vfstab</i>
          umount /apps
          mount /apps
          metattach d40 d42
          </pre>

          Since you have been writing to the c1t0d0s4 device instead of the metadevice, I'm not sure the two mirrors are in sync and mounting d40 without resyncing the mirror could result in loss of data.
          • 2. Re: Mirror Mirror
            bigdelboy
            >

            >
            So tell me, is slice 4 being mirrored or not? Is the "fix" as easy as just changing vfstab to /dev/md/dsk/d40?
            I suspect that action might cause you to fatally corrupt your filesystem.

            ....

            It is probable c1t0d0s4 is good, c1t1d0s4 is degraded.


            ....

            I would probably want to take a backup of what you have currently.

            .....

            I would probably want to be doing a metadetach to break off he bad mirror, then remount thange the vfstab to reference and mount d40, and metattach to resync the 'yffy' mirror d42 from the bad.

            Maybe an fsck in there might be good..

            ....

            IMHO Dont trust what I say ... make a plan and be very very safe and careful.

            Edited by: bigdelboy on 22-Jan-2013 08:18 ... okay I see you have had what looks like a good posting while I have been composing this.