Adding a Physical Disk as a Mirror to an Existing Zpool
Recently the disk that my syspool sits on started to lock up on my Nexenta (NCP) server. I decided to take this opportunity to set up a mirror to migrate the syspool (rpool) to another disk. Attaching a disk as a mirror is normally pretty easy, but this disk did not have any slices on it. Below is how I was able to mirror the OS and migrate to a new syspool disk with out taking any downtime.
First present a new disk to the server and rescan for the disk.
\# devfsadm -c disk
Now check for the disk.
\# echo |format
Searching for disks...done
AVAILABLE DISK SELECTIONS:
0. c8t0d0
/[email protected],0/pci15ad,[email protected]/[email protected],0
1. c8t1d0
/[email protected],0/pci15ad,[email protected]/[email protected],0
2. c8t2d0
/[email protected],0/pci15ad,[email protected]/[email protected],0
...
Specify disk (enter its number): Specify disk (enter its number):
In this case c8t1d0 is my new disk. Below is my existing syspool (please ignore the older format message. I am still running 26 on my syspool)
\# zpool status syspool
pool: syspool
state: ONLINE
status: The pool is formatted using an older on-disk format. The pool can
still be used, but some features are unavailable.
action: Upgrade the pool using 'zpool upgrade'. Once this is done, the
pool will no longer be accessible on older software versions.
scan: scrub repaired 0 in 0h10m with 0 errors on Mon Aug 13 09:02:23 2012
config:
NAME STATE READ WRITE CKSUM
syspool ONLINE 0 0 0
c8t0d0s0 ONLINE 0 0 0
errors: No known data errors
So we will need to attach the disk as a mirror of c8t0d0s0. The problem is that c8t1d0 does not have a slice, so we can either create one using partition in format, or we can clone the slice from c8t0d0s0. Below we will clone the slice from c8t0d0s0.
\# prtvtoc /dev/dsk/c8t0d0s0 |fmthard -s - /dev/rdsk/c8t1d0s0
fmthard: New volume table of contents now in place.
Now let’s add the disk as a mirror to c8t0d0s0. The -f is to force the operation.
\# zpool attach -f syspool c8t0d0s0 c8t1d0s0
Now we need to install grub to make the new disk bootable.
[email protected]:/boot/grub# installgrub /boot/grub/stage1 /boot/grub/stage2 /dev/rdsk/c8t1d0s0
stage1 written to partition 0 sector 0 (abs 4096)
stage2 written to partition 0, 274 sectors starting at 50 (abs 4146)
Let’s check the status of the resilver.
\# zpool status syspool
pool: syspool
state: ONLINE
status: The pool is formatted using an older on-disk format. The pool can
still be used, but some features are unavailable.
action: Upgrade the pool using 'zpool upgrade'. Once this is done, the
pool will no longer be accessible on older software versions.
scan: resilvered 6.51G in 0h4m with 0 errors on Mon Aug 13 09:07:23 2012
config:
NAME STATE READ WRITE CKSUM
syspool ONLINE 0 0 0
mirror-0 ONLINE 0 0 0
c8t0d0s0 ONLINE 0 0 0
c8t1d0s0 ONLINE 0 0 0
errors: No known data errors
So now it is setup and ready to run as a mirrored zpool. In my case I wanted to remove the original drive, which can be done with the following command.
\# zpool detach syspool c8t1d0s0
I would recommend running the syspool on a mirror, as I will when I replace the original disk.
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