[ovirt-users] Bug in Snapshot Removing

[Adam Litke]

On 03/06/15 07:36 +0000, Soeren Malchow wrote:
>Dear Adam
>
>First we were using a python script that was working on 4 threads and
>therefore removing 4 snapshots at the time throughout the cluster, that
>still caused problems.
>
>Now i took the snapshot removing out of the threaded part an i am just
>looping through each snapshot on each VM one after another, even with
>³sleeps² inbetween, but the problem remains.
>But i am getting the impression that it is a problem with the amount of
>snapshots that are deleted in a certain time, if i delete manually and one
>after another (meaning every 10 min or so) i do not have problems, if i
>delete manually and do several at once and on one VM the next one just
>after one finished, the risk seems to increase.

Hmm.  In our lab we extensively tested removing a snapshot for a VM
with 4 disks.  This means 4 block jobs running simultaneously.  Less
than 10 minutes later (closer to 1 minute) we would remove a second
snapshot for the same VM (again involving 4 block jobs).  I guess we
should rerun this flow on a fully updated CentOS 7.1 host to see about
local reproduction.  Seems your case is much simpler than this though.
Is this happening every time or intermittently?

>I do not think it is the number of VMS because we had this on hosts with
>only 3 or 4 Vms running
>
>I will try restarting the libvirt and see what happens.
>
>We are not using RHEL 7.1 only CentOS 7.1
>
>Is there anything else we can look at when this happens again ?

I'll defer to Eric Blake for the libvirt side of this.  Eric, would
enabling debug logging in libvirtd help to shine some light on the
problem?

-- 
Adam Litke