[libvirt] [RFC] Live disk snapshot API

[Eric Blake]

On 01/06/2011 07:37 AM, Nicolas Sebrecht wrote:
> The 06/01/11, Jiri Denemark wrote:
> 
>> Disk snapshot API needs to be general and flexible enough to support various
>> storage and snapshot methods. Examples of what can be used for creating disk
>> snapshots are: QEMU qcow2 snapshots, LVM snapshots, filesystems with snapshot
>> support (btrfs, zfs, ...), enterprise storage.
>>
>> Moreover, method used to create disk snapshot does not have to be determined
>> by disk type. One can have a qcow2 disk stored on btrfs inside lvm logical
>> volume; snapshot of such disk can be done at any of the three levels.
> 
> What would be the value of this API over a snapshot of the filesystem
> done from inside the domain?

Management:  It is easier to have your management software contact the
hosts of each VM to trigger the snapshot, rather than having to know how
to talk to each VM to have the VM do a disk snapshot.

Destination: a filesystem snapshot taken from within the domain can only
target virtual disks also exposed to the domain.  A disk snapshot taken
from the host, on the other hand, can place the snapshot in external
storage not visible from within the domain.

probably other advantages as well

-- 
Eric Blake   eblake at redhat.com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org

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