zfs discuss - Oct 2008 - zfs snapshot stalled?

Hi all,

I''ve just seen something weird. On a zpool which looks a bit busy right
now (~ 100 read op/s, 100 kB/s) I started a zfs snapshot about an hour
ago. Until now, a taking a snapshot took usually at few seconds at most
even for largish ~TByte file systems. I don''t know if the read IOs are
currently related to the snapshot itself or if another user doing this
since I have not looked prior to taking the snapshot.

My remaining questions after searching the web:

(1) Is it common that snapshots can take this long?
(2) Is there a way to stop it if one assumes somethings went wrong? I.e.
is there a special signal I could send it?

Thanks for any hint

Carsten
-- 
Dr. Carsten Aulbert - Max Planck Institute for Gravitational Physics
Callinstrasse 38, 30167 Hannover, Germany
Phone/Fax: +49 511 762-17185 / -17193
http://www.top500.org/system/9234 | http://www.top500.org/connfam/6/list/31

Hi again,

brief update:

the process ended successfully (at least a snapshot was created) after
close to 2 hrs. Since the load is still the same as before taking the
snapshot I blame other users'' processes reading from that array for the
long snapshot duration.

Carsten Aulbert wrote:
> My remaining questions after searching the web:
> 
> (1) Is it common that snapshots can take this long?
> (2) Is there a way to stop it if one assumes somethings went wrong? I.e.
> is there a special signal I could send it?
> 
> Thanks for any hint
> 
> Carsten