Hi,

I have encountered this before. Some operating systems may have bind-mounts 
that let a device appear multiple times in the mount list. Unfortunately the 
guest agent is not smart enough to consider a device that has been frozen as 
succesfull and keep going. This causes this specific error.

To verify this scenario, have a look at your list of mounts and see whether the 
same device appears multiple times, or whether other suspicious bind mounts 
appear.

Christian

> On 30 May 2016, at 09:31, Dominique Ramaekers 
> <[email protected]> wrote:
> 
> Hi,
> 
> I use external snapshots to backup my guests. I use the 'quiesce' option to 
> flush and frees the guest file system with the qemu guest agent.
> 
> With the exeption of one guest, this procedure works fine. On the 'unwilling' 
> guest, I get this error message:
> "ERROR 2016-05-25 00:51:19 | T25-bakVMSCmsrvVH2 | fout: internal error: 
> unable to execute QEMU agent command 'guest-fsfreeze-freeze': failed to 
> freeze /: Device or resource busy"
> 
> I don't think this is not some sort of time-out error, because activation of 
> the fsfreeze and the error message happen immediately after each other:
> 
> $ grep qemu-ga syslog.1
> May 25 00:51:19 CmsrvMTA qemu-ga: info: guest-fsfreeze called
> 
> This is the only entry of the qemu guest agent in syslog.
> 
> The difference of this guest in compresence with other, is that this guest 
> runs postfix + amavis + spammassasin + clamav
> 
> Any help would be appreciated.
> 
> More info:
> 
> $ sudo virsh version
> Compiled against library: libvirt 1.3.1
> Using library: libvirt 1.3.1
> Gebruikte API: QEMU 1.3.1
> Draaiende hypervisor: QEMU 2.5.0
> 
> $ virsh qemu-agent-command CmsrvMTA '{"execute": "guest-info"}'
> {"return":{"version":"2.5.0", ... 
> ,{"enabled":true,"name":"guest-fstrim","success-response":true},{"enabled":true,"name":"guest-fsfreeze-thaw","success-response":true},{"enabled":true,"name":"guest-fsfreeze-status","success-response":true},{"enabled":true,"name":"guest-fsfreeze-freeze-list","success-response":true},{"enabled":true,"name":"guest-fsfreeze-freeze","success-response":true},
>  ... }
> 
> For making an external snapshot, I use this command:
> $ virsh snapshot-create-as --domain CmsrvMTA sn1 --disk-only --atomic 
> --quiesce --no-metadata --diskspec vda,file=/srv/poolVMS/CmsrvMTA.sn1
> 
> Greetings,
> 
> Dominique.
> 

--
Christian Theune · [email protected] · +49 345 219401 0
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