Re: Problem with the use of domfsfreeze mountpoint option

[Shanzhi Yu <shyu@xxxxxxxxxx>]

---

From: "Eric Blake" <eblake@xxxxxxxxxx>
To: "Payes Anand" <payes.anand@xxxxxxxxxxxxx>, libvirt-users@xxxxxxxxxx
Sent: Wednesday, November 12, 2014 5:51:12 AM
Subject: Re: [libvirt-users] Problem with the use of domfsfreeze mountpoint option

On 11/11/2014 01:58 PM, Payes Anand wrote:
> Hi everybody,
>
> I am having a problem with the use of domfsfreeze command.
>
> It is freezing all the filesystems present on the domain,
>
> instead of freezing just the mountpoints provided.
>
> I am issuing the command--
>
> # virsh domfsfreeze <domain> --mountpoint <mountpoint>
>
> Output was-- Froze 3 filesystem(s)
>
>
> I want to freeze a particular mount point on the VM, so that i can
> take a snapshot using my own snapshot feature.
>
> Using library: libvirt 1.2.5
> Using API: QEMU 1.2.5
> Running hypervisor: QEMU 2.0.0

What version of qemu-guest-agent is running in the guest?
qemu-guest-agent doesn't support per-mountpoint freezing until the
introduction of guest-fsfreeze-freeze-list in qemu 2.2 (still unreleased).

>
> --Upgraded libvirt to 1.2.10, but that also didn't solve the problem.
>
> Am i missing something over here?
> Any help would be greatly appreciated.

I wonder if you may have uncovered a libvirt bug.  If the guest agent is
not capable of supporting per-mount freezing (because the agent is too
old), the command should fail rather than blindly freezing everything.
But to know for sure, it would be good to find the log messages for the
actual agent commands issued by libvirt, to make sure we were actually
trying to freeze just a single mount point.

On RHEL, the bug for adding FSFreeze function is this one :https://bugzilla.redhat.com/show_bug.cgi?id=1102457

And according commnet 10 in that bug, --mountpoint is not supported now.

Whether  you specify --mountpoing or not, it will always output

Froze 2 filesystem(s) or Thawed 2 filesystem(s)

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

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--

Regards
shyu

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