Re: [libvirt] RFCv2: virDomainSnapshotCreateXML enhancements

Hello Kevin, hello Eric, On Thursday 11 August 2011 12:00:46 Kevin Wolf wrote: > Am 11.08.2011 00:08, schrieb Eric Blake: >> Libvirt currently has a bug in that it only saves <domain>/<uuid> rather >> than the full domain xml along with a checkpoint - if any devices are >> hot-plugged (or in the case of offline snapshots, if the domain >> configuration is changed) after a snapshot but before the revert, then >> things will most likely blow up due to the differences in devices in use >> by qemu vs. the devices expected by the snapshot. > > Offline snapshot means that it's only a disk snapshot, so I don't think > there is any problem with changing the hardware configuration before > restoring it. > > Or does libvirt try to provide something like offline checkpoints, where > restoring would not only restore the disk but also roll back the libvirt > configuration? Try to load a VM state with the memory size changed in between and your VM is busted; been there, experienced that :-( So it's nice to do a snapshot before you play with your virtual hardware configuration and can go back there if things go wrong. 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.