guest-fsfreeze-freeze freezes all mounted block devices

Marc Roos M.Roos at
Mon Feb 17 09:03:27 UTC 2020

Hi Peter,

Should I assume that the virsh domfsfreeze, does not require the 
qemu-agent service in the guest?

PS. I couldn't find the result. Afaik it looks like it is returning the 
amount of frozen/thawed filesystem's

-----Original Message-----
Cc: libvirt-users
Subject: Re: guest-fsfreeze-freeze freezes all mounted block devices

On Fri, Feb 14, 2020 at 22:14:55 +0100, Marc Roos wrote:
> I wondered if anyone here can confirm that
> virsh qemu-agent-command domain '{"execute":"guest-fsfreeze-freeze"}'

Note that libvirt implements this directly via 'virsh domfsfreeze'. This 
is the corresponding man page entry:

  domfsfreeze domain [[--mountpoint] mountpoint...]
      Freeze mounted filesystems within a running domain to prepare for 
consistent snapshots.

      The --mountpoint option takes a parameter mountpoint, which is a 
mount point path of the filesystem to be frozen.
      This option can occur multiple times. If this is not specified, 
every mounted filesystem is frozen.

> Freezes all mounted block devices filesystems. So if I use 4 block 
> devices they are all frozen for snapshotting. Or just the root fs?

Since you are using agent passthrough where libvirt doesn't do any 
interpretation of what happens please refer to the appropriate QEMU 
agent documentation for the semantics of the command you've used.

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