Monday January 23, 2006 Converting a ZFS pool to be mirrored
So, the ZFS syntax is quite different to that of SVM which can lead to confusion. Ben Rockwood does a good job of explaning the difference, but does not show how to convert an un-mirrored ZFS pool into mirrored one. So, here's how to do it
o We start with a pool called realzfs (because it's made out of real devices rather than files)
# zpool list
NAME SIZE USED AVAIL CAP HEALTH ALTROOT
realzfs 544G 1.17G 543G 0% ONLINE -
o We can see that it is made up of 4 disks
# zpool status
pool: realzfs
state: ONLINE
scrub: none requested
config:
NAME STATE READ WRITE CKSUM
realzfs ONLINE 0 0 0
c3t0d0 ONLINE 0 0 0
c3t1d0 ONLINE 0 0 0
c3t2d0 ONLINE 0 0 0
c3t5d0 ONLINE 0 0 0
o The correct way is to attach a new device to each existing ldev e.g.
# zpool attach -f realzfs c3t0d0 c3t8d0
# zpool status
pool: realzfs
state: ONLINE
status: One or more devices is currently being resilvered. The pool will
continue to function, possibly in a degraded state.
action: Wait for the resilver to complete.
scrub: resilver in progress, 99.99% done, 0h0m to go
config:
NAME STATE READ WRITE CKSUM
realzfs ONLINE 0 0 0
mirror ONLINE 0 0 0
c3t0d0 ONLINE 0 0 0
c3t8d0 ONLINE 0 0 0 178.3 resilvered
c3t1d0 ONLINE 0 0 0
c3t2d0 ONLINE 0 0 0
c3t5d0 ONLINE 0 0 0
# zpool attach -f realzfs c3t1d0 c3t9d0
# zpool attach -f realzfs c3t2d0 c3t10d0
# zpool attach -f realzfs c3t5d0 c3t11d0
o Finally we see all our ldevs mirrored.
# zpool status
pool: realzfs
state: ONLINE
scrub: resilver completed with 0 errors on Mon Jan 23 15:26:16 2006
config:
NAME STATE READ WRITE CKSUM
realzfs ONLINE 0 0 0
mirror ONLINE 0 0 0
c3t0d0 ONLINE 0 0 0
c3t8d0 ONLINE 0 0 0
mirror ONLINE 0 0 0
c3t1d0 ONLINE 0 0 0
c3t9d0 ONLINE 0 0 0
mirror ONLINE 0 0 0
c3t2d0 ONLINE 0 0 0
c3t10d0 ONLINE 0 0 0
mirror ONLINE 0 0 0
c3t5d0 ONLINE 0 0 0
c3t11d0 ONLINE 0 0 0
o The WRONG way to do it is as follows:-
# zpool add -f realzfs mirror c3t8d0 c3t9d0 c3t10d0 c3t11d0
# zpool status
pool: realzfs
state: ONLINE
scrub: resilver completed with 0 errors on Mon Jan 23 15:26:16 2006
config:
NAME STATE READ WRITE CKSUM
realzfs ONLINE 0 0 0
c3t0d0 ONLINE 0 0 0
c3t1d0 ONLINE 0 0 0
c3t2d0 ONLINE 0 0 0
c3t5d0 ONLINE 0 0 0
mirror ONLINE 0 0 0
c3t8d0 ONLINE 0 0 0
c3t9d0 ONLINE 0 0 0
c3t10d0 ONLINE 0 0 0
c3t11d0 ONLINE 0 0 0
Which is 4 single disk ldevs and one 4way mirrored ldev. NOT 4 mirrored ldev's which is what we actually wanted.
( Jan 23 2006, 04:13:50 PM GMT )
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