zfs discuss - May 2007 - Extremely long ZFS destroy operations

We''ve Solaris 10 Update 3 (aka 11/06) running on an E2900 (24 x 96). On
this server we''ve been running a large SAS environment totalling well
over 2TB. We also take daily snapshots of the filesystems and clone them for use
by a local zone. This setup has been in use for well over 6 months.

Starting Monday I started making a second clone from the same snapshot to
facilitate quick access to day old image of data in the global zone.
I''ve started noticing that my ZFS destroy operations are inordinately
long with the second clone in place (I''m using zfs destroy -Rf <snap
name>). The degradation is close to an order of magnitude; my destroys now
take 6-7 minutes while they took sub minute in the past.

Any thoughts? Thanks.
 
 
This message posted from opensolaris.org

I''ve since stopped making the second clone when I realized the
.zfs/snapshot/<snapname> still exists after the clone operation is
completed. So my need for the local clone is met by the direct access to the
snapshot.

However, the poor performance of the destroy is still valid. It is quite
possible that we might create another clone for reasons beyond my original
reason.

Why is the destroy so slow with the second clone in play? Thanks.
 
 
This message posted from opensolaris.org

On Wed, 9 May 2007, Anantha N. Srirama wrote:
> However, the poor performance of the destroy is still valid. It is quite
> possible that we might create another clone for reasons beyond my
> original reason.
There are a few open bugs against destroy.  It sounds like you may be
running into 6509628 ("unmount of a snapshot (from ''zfs
destroy'') is
slow")


Regards,
markm