Hello everybody, Many requests for Xen are: we need a snapshot mechanism like VMWare. Xen does not provide the feature that allows this kind of snapshot. With VMWare snapshot, you can do a snapshot on an alive VM, just by clicking a button or issuing a command. The VM is kept alive as nothing happened. When a VM is reverted from a snapshot, it runs at the same state it was when the snapshot occured (except network connections, I suppose). To do this, VMWare takes a snapshot of both the memory and the disks. That is the point missed by xen: there is no way to synchronise a kind of suspend with a disk snapshot. This should be easy to implement, by reusing the live migration feature. We need to have 2 new xm commands: - *snap_and_pause*: this function dump the memory of the running VM in a file, using the way the live migration does (instead of sending data through the network, they are stored in a file). After that, the VM is left in a paused state. - *start_from_snap*: a VM is created from a file previously created by the previous command, as a VM magically appears on the target dom0 when you live-migrate a VM. With those 2 commands, the snapshot becomes trivial to script: - run "snap_and_pause" on the VM - take a disk snapshot by the appropiate way depending your setup (LVM snapshots, etc) - unpause the VM To revert to a snapshot: - switch the disk snapshot with the original - run "start_from_snap". What are your opinions about this? Is it feasable? Have I missed some point? Several month ago, I heard about a patch on the live migration function to store the memory in a file instead of sending it through the network. I didn''t retreive the thread. _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users