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(a)redhat.com +1-801-349-2682
Libvirt virtualization library http://libvirt.org