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Re: [libvirt] RFCv2: virDomainSnapshotCreateXML enhancements

On 08/12/2011 02:56 AM, Philipp Hahn wrote:
For -loadvm to work you have to call kvm with the nearly same command
line arguments again; what may change you probably know better than me.
For I thinks it's essential to store the VM consiguration with the
snapshot, which would be the qemu command line arguments, which is
equivalent to libvirts XML description.

Yes, I understand this. I was talking about snapshots taken while the VM
is shut off, where it's not as clear.

I think is very useful for offline snapshots too, since your VM might depends
on the exact qemu command line: think of (incomplete) RAIDs or udevs
persistent MAC address rules.

But for consistency it's probably
better to do the same with offline and online snapshots, so what libvirt
implements (or was it only Eric's plan?) is fine here.

My plan is to do full-scale revert to the embedded <domain>, whether the checkpoint was online or offline. To go from running to an online checkpoint when the <domain> is still ABI compatible, I will continue to use the 'loadvm' monitor command; for all other cases, loading an online checkpoint will create a new qemu process with the '-loadvm' command line argument.

Currently as of libvirt-0.9.4 the domain configuration is not saved with the
snapshot. I have implemented that for our internal 0.8.4 version as a working
proof-on-concept, but Eric is now reviewing the whole picture.

Yep, I'm heavily re-using Philipp's proof-of-concept in the part of my patch series that embeds the full <domain> into <domainsnapshot>.

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

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