ZFS. split a mirror, and remount "2nd" half
in [Solaris]
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From: jay on 4 May 2010 10:54 On May 3, 7:13 pm, ITguy <southa...(a)gmail.com> wrote: > > > > i have a mirrored zfs filesystem, but it's a mirror > > > > of the full disk -- so there's no issues w/ slice > > > > sizes or disk partitioning. > > > > > i want to split the mirror and then re-mount the > > > > now "non-operating" part. once i detach the > > > > mirror i can remove the device. all that > > > > goes just fine. (maybe.) i thought the thing > > > > to do would be to come up with a new pool > > > > and try to put the device in there. but that > > > > empties the prior contents of the disk. > > What does splitting the mirror do for you that a snapshot/clone does > not? If you really need the additional space, you can snapshot, > detach a mirror, create a new second pool from the detached disk, and > zfs send/receive a copy over to the new pool. Not as efficient as a > zpool split, but gets the job done. this is for several reasons, but the main one is disaster recovery. the final answer to my question is -- use zpool split when it finally emerges. detaching the mirror erases some info on disk that's needed to import it. however, this assumes that you have enough of a system left that you can run zpool split. if your cpu has melted the replies i got from oracle indicate the disks, even if they're otherwise okay, might be unusable. so my position is ufs is a better choice in disaster recovery scenarios. thanks to all who tried to help. j.
From: hume.spamfilter on 4 May 2010 11:58 jay <bigcrater(a)gmail.com> wrote: > enough of a system left that you can run zpool split. if your cpu > has melted the replies i got from oracle indicate the disks, even if > they're otherwise okay, might be unusable. so my position is What did Oracle say that implied that? -- Brandon Hume - hume -> BOFH.Ca, http://WWW.BOFH.Ca/
From: cindy on 4 May 2010 12:00
On May 4, 8:54 am, jay <bigcra...(a)gmail.com> wrote: > On May 3, 7:13 pm, ITguy <southa...(a)gmail.com> wrote: > > > > > > > > i have a mirrored zfs filesystem, but it's a mirror > > > > > of the full disk -- so there's no issues w/ slice > > > > > sizes or disk partitioning. > > > > > > i want to split the mirror and then re-mount the > > > > > now "non-operating" part. once i detach the > > > > > mirror i can remove the device. all that > > > > > goes just fine. (maybe.) i thought the thing > > > > > to do would be to come up with a new pool > > > > > and try to put the device in there. but that > > > > > empties the prior contents of the disk. > > > What does splitting the mirror do for you that a snapshot/clone does > > not? If you really need the additional space, you can snapshot, > > detach a mirror, create a new second pool from the detached disk, and > > zfs send/receive a copy over to the new pool. Not as efficient as a > > zpool split, but gets the job done. > > this is for several reasons, but the main one is disaster recovery. > > the final answer to my question is -- use zpool split when it > finally emerges. detaching the mirror erases some info on disk > that's needed to import it. > > however, this assumes that you have > enough of a system left that you can run zpool split. if your cpu > has melted the replies i got from oracle indicate the disks, even if > they're otherwise okay, might be unusable. so my position is > ufs is a better choice in disaster recovery scenarios. > > thanks to all who tried to help. > > j. Jay, I didn't realize you were planning for root pool disaster recovery. In that case, zpool split is not supported for root pools so that wouldn't have helped you any way. You can configure a mirrored root pool with two or even 3 disks to help reduce downtime due to hardware failures. As was already mentioned, you can keep root pool snapshots on a remote system for disaster recovery purposes. All of these steps are described in detail, here: http://www.solarisinternals.com/wiki/index.php/ZFS_Troubleshooting_Guide ZFS Root Pool Recovery I don't see how this process is much different from using ufsdump and ufsrestore to restore full or incremental backups to restore a UFS root file system on bare metal. In the Solaris 10 10/09 release, you can create a flash archive of your ZFS root pool for recovery purposes. This method is described here: http://docs.sun.com/app/docs/doc/819-5461/githk?l=en&a=view Thanks, Cindy |