the holcasaur

  pool: exportpool
 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.
 scrub: none requested
config:

        NAME        STATE     READ WRITE CKSUM
        exportpool  ONLINE       0     0     0
          c0t0d0s7  ONLINE       0     0     0
          c0t1d0    ONLINE       0     0     0

errors: No known data errors

So, for a verbal explanation, it’s a striped pool made up of one whole disk, plus one partition on c0t0d0, which also happens to be the root disk, where there are numerous other partitions housing the ufs filesystems.  Those partitions are completely unmirrored.  Oh, and it’s out of date, to boot.

If either disk goes, the whole system goes.  The performance for the zpool will be completely weird depending on which disk it hits.  And to top it all off, they are forever entangled now.  This is set in stone, unless a complete system wipe can be performed.

Good job.

With apologies to mentos.

So wordpress 2.3 is out now. I thought, might as well upgrade, why the fuck not. But just to be sure, I took a snapshot of the filesystems on which apache and mysql live.

First, I shut down the services…

svcadm disable -t apache2
svcadm disable -t mysql

Then took a snapshot of the data…

zfs snapshot data/apache2@pre-2.3
zfs snapshot data/mysql@pre-2.3

Performed the upgrade…

Hello.

Re-enabled the services…

svcadm enable mysql
svcadm enable apache2

Got a bunch of SQL errors… Well fuck, now what. My blog is hosed. Oh wait…

Re-disabled the services…

svcadm disable -t apache2
svcadm disable -t mysql

Roll back the snapshots…

zfs rollback data/mysql@pre-2.3
zfs rollback data/apache2@pre-2.3

Re-re-enabled the services…

svcadm enable mysql
svcadm enable apache

Viola! errr Voila! I knew those french classes would come in handy.

In my previous job, we had a few issues of zfs. These were completely outweighed by the benefits, and anyway, I knew patches would come along eventually to fix them. Looks like, at least for two problems, they’re on the way.

ZFS and NFS latency issues begone: separate ZILs, especially on NVRAM, greatly accelerate small writes.

ZFS will now be much better at aligned writes, which dbs apparently really like.

Wonder how much the NVRAM cards cost…