[libvirt-users] Live snapshot merging (qemu 2.0)

Thomas Stein himbeere at meine-oma.de
Tue Apr 22 13:03:36 UTC 2014

Am 22.04.14 14:00, schrieb Eric Blake:
> On 04/22/2014 01:47 AM, Thomas Stein wrote:
>> Hello.
>> The Changelog of qemu-2.0.0 mentioned "Live snapshot merging". Someone
>> has an idea what could be ment by this? I'm asking because i'm still
>> struggling with finding a reliable backup solution for running kvm
>> machines. Blockcopy is my current solution.
> "Live snapshot merging" means going from a backing chain of "base <-
> img" to "base" by merging the contents of img into base.  Libvirt does
> not yet support this action, but we are getting closer with our work on
> tracking the entire backing chain in domain XML.
> Current libvirt is able to support some chain shortening operations with
> older qemu: libvirt can do snapshot merging of any backing file (taking
> "base <- snap1 <- snap2" to "base <- snap2" by committing snap1 into
> base), as well as pulling content into the active layer (going from
> "base <- snap1 <- snap2" to "base <- snap2" by pulling snap1 into
> snap2).  And as you mentioned, using blockcopy also allows libvirt to
> pivot to a new shorter backing chain.

Thanks Eric for the explanation.


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