[Libvir] Re: Next features and target for development
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.
Regards,
Anthony Liguori
With qemu-img one can create a new disk image that depends on an old
one and
every changes are written to the new one. But maybe it is also possible to do
this with running machines, when one suspends them, creates the new qcow2
image and starts the machine again, but I have never tried this.
Regards,
Till