Dear Thomas,
Thank you very much - that is a very helpful diagnostic method / alarm bell!
Further investigating my issue, I determined that I often get "error: block copy
still active: disk 'vda' not ready for pivot yet". The more limited the
hardware is, the higher the likelihood, I think. The underlying storage is gluster and I
think that this is due to locking issues in slower environments. Therefore, I added a
"sleep" command ahead of the "blockcommit" command. That does seem to
be OK as a workaround in most cases.
Nevertheless, I am not sure if there are other causes as well and if there are better ways
to prevent this issue as the sleep command is probably not the most elegant way.
Regards,
Michael
-----Ursprüngliche Nachricht-----
Von: libvirt-users-bounces(a)redhat.com [mailto:libvirt-users-bounces@redhat.com] Im Auftrag
von Thomas Stein
Gesendet: Dienstag, 26. Juli 2016 10:53
An: 'libvirt-users(a)redhat.com' <libvirt-users(a)redhat.com>
Betreff: Re: [libvirt-users] Live Disk Backup
Am 26.07.16 um 10:25 schrieb Prof. Dr. Michael Schefczyk:
Dear All,
using CentOS 7.2.1511, and libvirt from ovirt repositories (currently
1.2.17-13.el7_2.5, but without otherwise using ovirt) I am regularly
backing up my VMs which are on qcow2 files. In general, I am trying to
follow
http://wiki.libvirt.org/page/Live-disk-backup-with-active-blockcommit
A typical backup script would be
#!/bin/bash
dt=`date +%y%m%d`
if virsh dominfo dockers10a | grep -q -E '^Status: *laufend|^State: *running'
then
virsh snapshot-create-as --domain dockers10a dockers10a --diskspec
vda,file=/home/dockers10asnap.qcow2 --disk-only --no-metadata --atomic
cp /kvm01/dockers10a.qcow2 /backup/dockers10a$dt.qcow2 virsh
blockcommit dockers10a vda --active --verbose --pivot virsh
snapshot-delete dockers10a dockers10a rm /home/dockers10asnap.qcow2 fi
I am fully aware that the third line from the end "virsh snapshot-delete ..."
will fail under regular circumstances. It is just there as a precaution to delete
unnecessary snapshots should a previous backup have failed.
For some time, I am noticing that from time to time backup fails in the way that the xml
definition file of the VM backed up keeps the temporary file (in the example above
/home/dockers10asnap.qcow2) as the source file. Then, at least upon rebooting the host, it
will be unable to restart the VM. In addition, lots of other troubles can arise (following
backups failing, storage issues).
I am using a similar setup on four hosts. It seems that the better the resources of the
host are, the lower the likelihood of the problem occurring - but that cannot be an
acceptable state.
Can someone please point me to how to avoid this?
Here is what i do. I check the VM if it is running from a snapshot first.
if [[ $(virsh domblklist vmmachinename) = *weekly* ]]; then
echo "Found activ snapshot vmmachinename" | mail -s "Found activ snapshot
vmmachinename" emailaddress
else
cheers
t.
Regards,
Michael Schefczyk
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