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2 Replies Latest reply: Jan 22, 2013 8:19 AM by bigdelboy RSS

Mirror Mirror

982087 Newbie
Currently Being Moderated
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 Pro
    Currently Being Moderated
    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 Pro
    Currently Being Moderated
    >

    >
    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.

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