[libvirt-users] Problem executing VM backups

[Kashyap Chamarthy]

On Wed, Jun 22, 2016 at 08:59:24AM +0200, Markus Ellinger wrote:
> Hi everyone,
> 
> we are suddenly having a problem with executing our backup jobs. For a long
> time, we have used a shell script which contains the following code to
> backup all our virtual machines:
> 
>         for domain in Testserver Faktura Fileserver Gitolite Jenkins Nexus
> SimpleHelp VpnGateway Wiki; do
>                 echo -n "$(date +"%Y-%m-%d %H:%M:%S") starting backup for vm
> ${domain} ... " >> ${vmlog}
>                 virsh dumpxml --security-info ${domain} >
> ${vmdir}/${domain}.xml
>                 virsh undefine ${domain}  >> ${vmlog}
>                 virsh blockcopy ${domain}
> /var/lib/libvirt/images/${domain}.img ${vmdir}/${domain}.img --wait --finish
> >> ${vmlog}
>                 virsh define ${vmdir}/${domain}.xml >> ${vmlog}
>         done
 
[...]

>                  root at gfii-host:~# virsh undefine Gitolite
>                  error: Failed to undefine domain Gitolite
>                  error: Requested operation is not valid: cannot undefine
> transient domain
> 
>                  root at gfii-host:~# virsh blockcopy Gitolite
> /var/lib/libvirt/images/Gitolite.img /tmp/test-blockcopy-gitolite.img --wait
> --finish
>                  error: block copy still active: disk 'vda' already in
> active block job
> 
>                  root at gfii-host:~# virsh blockjob Gitolite
> /var/lib/libvirt/images/Gitolite.img
>                  No current block job for
> /var/lib/libvirt/images/Gitolite.img

I was going to suggest that in the even if you do see an active block
job here, then you could've aborted it via:

    $ virsh blockjob Gitolite /path/to/disk/ --abort

But you say there's no active block operation.

(I doubt it will help, but you might want to supply "--info" to that
`virsh blockjob` query.  From the manual: "In --info mode, the active
job information on the specified disk will be printed.")

>                  root at gfii-host:~# virsh define
> /var/local/backup/vms/2016-06-22T013001/Gitolite.xml
>                  error: Failed to define domain from
> /var/local/backup/vms/2016-06-22T013001/Gitolite.xml
>                  error: block copy still active: domain has active block job

Although I've seen some bug reports (and were fixed) in the past of this
error during different block operations, but I can't pin-point the exact
reason here why you're seeing it.

You might want to enable libvirt logging filters (in
/etc/libvirt/libvirtd.conf) to get some more useful details:

    log_filters="1:libvirt 1:qemu 1:conf 1:security 3:event 3:json 3:file 3:object 1:util"
    log_outputs="1:file:/var/log/libvirt/libvirtd.log"

(Don't forget to restart libvirt daemon before performing your test.)


While we're at it, here's another another way to perform live backups
(which is slightly more efficient), if it is of any help:

    http://wiki.libvirt.org/page/Live-disk-backup-with-active-blockcommit

> Of course we tried to start/stop the virtual machines, rebooted the whole
> host multiple times etc., but the problem comes back every night.
> 
> The machine is a Debian Wheezy machine with current updates. We are using
> the qemu-kvm package from wheezy-backports to enable blockcopy support.

Specifying explicit versions will be convenient.

 

-- 
/kashyap