Reducing ZFS blocksize to improve Cyrus write performance ?

[Vincent Fox]

  So to my mind, the downside of ZFS flush disable is.....

Data on disk may not be as current in the unlikely event
of power outage.  In point of fact MOST filesystem do not operate
in journalled data mode anyhow and most people just don't
realize this fact.   The default for Linux EXT filesystems with journalling
is just to ensure metadata integrity, and few people set data journalling
because it costs performance.

However you set it, ZFS is not going to come up with an fsck
prompt resulting in hours of single-user downtime.  Which is
what really matters the most eh?