On Wed, Jul 11, 2007 at 08:59:08AM -0500, Anthony Liguori wrote: > Till Maas wrote: > >On Mi Juli 11 2007, Richard W.M. Jones wrote: > > > >>I'm interested to know how VirtualBox / VMWare deal with disk storage. > >>Do they provide their own storage subsystems which support this or do > >>they interact with things like LVM? > > > >The use their own subsystem. VMWare uses .vmdk files to store the harddisk > >contents. When a snapshot is created, it creates a new one that depends on > >the old one and stores every change in the new one. When the machine is > >running during the snapshot, the complete state of the machine is stored, > >too. I guess VirtualBox does it similiar. > > > >Qemu also provides this feature, except that afaik it is only possible to > >savely create snapshots of powered off machines with the qcow2 image type. > > This is not correct. QEMU has supported (for a very long time) the > ability to save/restore snapshots of running machines. In QEMU 0.9.0, > instead of saving snapshots to an external file, snapshots are saved > along with disk snapshots to the actual disk file. This of course > requires that the disk format support this and currently qcow2 is the > only format that does. Which makes it rather useless - pretty much all my guests are either LVM or partitions, and sometimes raw files. I understand why this was done because it lets you do incremental checkpointing & restore. I think it'd be usefult to also add back support for saving to external files. I was looking at the code & think it would be really very easy to do, without impacting current code. Dan. -- |=- Red Hat, Engineering, Emerging Technologies, Boston. +1 978 392 2496 -=| |=- Perl modules: http://search.cpan.org/~danberr/ -=| |=- Projects: http://freshmeat.net/~danielpb/ -=| |=- GnuPG: 7D3B9505 F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 -=| -- Libvir-list mailing list Libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list