[libvirt] A question for external snapshots with flag“VIR_DOMAIN_SNAPSHOT_CREATE_QUIESCE”

[Martin Kletzander]

On Tue, Feb 28, 2017 at 09:22:16AM -0600, Eric Blake wrote:
>please don't include libvir-list-owner in your mails.  Also, it would be
>nice if you could convince your mailer to wrap long lines.
>

Also sending the question multiple times from multiple e-mail addresses
makes bad reputation and creates huge mess.  I'm also not at all in
favour of adding random people in Cc.  You're basically just spamming
their inboxes.

>On 02/28/2017 06:37 AM, lizhengui wrote:
>> Hello, I got a question here. When we create consistent active
>external snapshots with flag “VIR_DOMAIN_SNAPSHOT_CREATE_QUIESCE” , the
>qemuDomainSnapshotFSFreeze will be called firstly to freeze all
>filesystems in vm, and then create snapshots. For windows vm, freezing
>filesystems used by vss service. If IO pressure in vm is too big or
>internal error happened in vss , freezing filesytems will failed , and
>qemuDomainSnapshotFSFreeze returns 0 which meaning that no filesystems
>are frozen.
>
>That sounds like a bug in the qga implementation for freezing file
>systems on Windows - if the system is not frozen, qga should return
>failure, not 0.  Since libvirt doesn't maintain qga, this should
>probably be reported to the qemu folks.
>
>> In the function qemuDomainSnapshotCreateActiveExternal, libvirt
>creates external snapshots all the same in such a situation that
>qemuDomainSnapshotFSFreeze returns 0, but the created snapshots are not
>consistent snapshots in such a situation . So shouldn't we abandon
>creating snapshots and goto cleanup in the situation that
>qemuDomainSnapshotFSFreeze returns 0?
>
>Yes, even if qga behavior is patched, libvirt should probably figure out
>if it is feasible to work around existing broken behavior.
>

According to our comment which states that the return value is number of
filesystems freezed, I expected it to be documented behaviour.  If that
is the case, we can fix it right now.  See my response in the other
thread.

>-- 
>Eric Blake   eblake redhat com    +1-919-301-3266
>Libvirt virtualization library http://libvirt.org
>




>--
>libvir-list mailing list
>libvir-list at redhat.com
>https://www.redhat.com/mailman/listinfo/libvir-list

-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 833 bytes
Desc: Digital signature
URL: <http://listman.redhat.com/archives/libvir-list/attachments/20170228/7ba9b760/attachment-0001.sig>