Today I upgraded Owncloud from (FreeBSD) ports, 9.1.0_1 -> 9.1.1. All went fine, but the file integrity check never seemed to end. Could not find a way around it, skip it, fake it or whatever (which would be nice), so I started the upgrade process via command-line (occ upgrade) making a trace easier. Then I noticed that the upgrade process was doing a file integrity check on .zfs/snapdir/* and thus reading multiple data dirs of the same (twice a day, a month worth of zfs snapshots).
In ZFS, the .zfs snapdir is hidden by default - I had made it visible a couple of days ago for some other issue. So I guess you could say that I caused the issue myself.
Feature Request: Owncloud could ignore the .zfs snapdir by default (or as a default option), or perhaps warn if a .zfs/{snapdir,shares} directory is found as a file integrity check would take ages otherwise, making Owncloud more or less unusable once the upgrade process was started.