Re: close() taking minutes (ZFS related)

It seems I have found the reason for the strange behaviour: it is
dedup.

The pool is configured to use dedup, because it carries all my jail OS
installation, which are very similar. But dedup makes no sense on
database filesets, and apparently it has very bad effects on real
workload: it creates immense write-amplification (about factor 4)
and probably other bad effects (memory is not the issue here).

I don't think it should lockdown the entire pool, but it is
understandable that it creates a logical relation between the
different filesets.