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Re: [libvirt] [PATCH 1/3] Add test for transient domain snapshot management



On 08/26/2011 08:16 AM, Daniel P. Berrange wrote:
From: "Daniel P. Berrange"<berrange redhat com>

The test case validates the core lifecycle operations on
persistent domains with snapshots. A transient domain
should allow snapshots to be created while running. It
should be possible to destory and restart the domain

s/destory/destroy

and still have snapshots present.

See my reply to 0/3. I think this test is making an invalid assumption. If we leave stale snapshot metadata behind, then create a new domain with different uuid but same name, then we are setting ourselves up for confusion. We _have_ to clean up the metadata at some point in time, either when a new domain is created whose name happens to match stale metadata from a previous domain, or when the last reference to a transient domain disappears. But if we also make it possible to reinstate metadata, via VIR_DOMAIN_SNAPSHOT_CREATE_REDEFINE, then the app managing a transient domain will be able to reinstate everything needed to be able to safely revert back to the snapshot storage (when the prior transient domain shut down, it was only the metadata that was lost, not the actual storage).

At any rate, thanks for making me think about this, and I guess I'd better get CREATE_REDEFINE working sooner rather than later.

--
Eric Blake   eblake redhat com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org


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