ZFS RaidZ2 with 24 drives?

[Thomas Burgess]

> I have  my suspicions that this means your filesystem is heavily
fragmented. I've had it happen to me on at least 3 pools, some of which were
not even close to full, yet rebuilding the pool restored much of the
performance. Hopefully with the block pointer rewrite support coming we will
get some tools to address this. Right now I am not even aware of a tool that
will check for fragmentation.
I'm pretty sure he is running on a brand new pool.

Originally he asked about creating a raidz2 vdev with 24 drives.  Then, he
said he "settled" for 2 12 drive vdevs.
Also, this being FreeBSD it might be awhile before we even see the block
pointer rewrite support even when it DOES hit.