On Wed, 2007-06-27 at 14:50 -0700, Darren Dunham wrote: > > Darren Dunham wrote: > > >> The problem I've come across with using mirror or raidz for this setup > > >> is that (as far as I know) you can't add disks to mirror/raidz groups, > > >> and if you just add the disk to the pool, you end up in the same > > >> situation as above (with more space but no redundancy). > > > > > > You can't add to an existing mirror, but you can add new mirrors (or > > > raidz) items to the pool. If so, there's no loss of redundancy. > > > > Maybe I'm missing some context, but you can add to an existing mirror > > - see zpool attach. > > It depends on what you mean by "add". :-) > > The original message was about increasing storage allocation. You can > add redundancy to an existing mirror with attach, but you cannot > increase the allocatable storage. >
With mirrors, there is currently more flexibility than with raid-Z[2]. You can increase the allocatable storage size by replacing each disk in the mirror with a larger sized one (assuming you wait for a re-sync ;-P ) Thus, the _safe_ way to increase a mirrored vdev's size is: Disk A: 100GB Disk B: 100GB Disk C: 250GB Disk D: 250GB zpool create tank mirror A B (yank out A, put in C) (wait for resync) (yank out B, put in D) (wait for resync) and voila! tank goes from 100GB to 250GB of space. I believe this should also work if LUNs are used instead of actual disks - but I don't believe that resizing a LUN currently in a mirror will work (please, correct me on this), so, for a SAN-backed ZFS mirror, it would be: Assuming A = B < C, and after resizing A, A = C > B zpool create tank mirror A B zpool attach tank A C (where C is a new LUN of the new size desired) (wait for sync of C) zpool detach tank A (unmap LUN A from host, resize A to be the same as C, then map back) zpool attach C A (wait for sync of A) zpool detach B I believe that will now result in a mirror of the full size of C, not of B. I'd be interested to know if you could do this: zpool create tank mirror A B (resize LUN A and B to new size) without requiring a system reboot after resizing A & B (that is, the reboot would be needed to update the new LUN size on the host). -- Erik Trimble Java System Support Mailstop: usca14-102 Phone: x17195 Santa Clara, CA Timezone: US/Pacific (GMT-0800) _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
