> >>>> My understanding is internal snapshots is obvious fast in both > >>>> deleting and reading, and I have similar questions, Dietmar, could > >>>> u tip more how you use this case while 2 snapshot layer exist? > >>> > >>> To be honest, I don't really understand what you talk about here. > >>> There are simply different storage types and file formats. There are > >>> several storage types with support for internal snapshots: > >>> > >>> * traditional qcow2 files on normal file system > >>> * newer file systems (zfs, btrfs) > >>> * lvm (new dm-thin pools) > >>> * RDB (ceph) > >>> * sheepdog > >>> * iSCSI and nexenta API > >>> *... > >>> > >>> And you simply want to allow an external library to create/remove > >>> the > >> snapshot for you. > >>> > >>> > >>> > >> I remember you have a patch enable take qcow2 internal snapshot > >> for every block device, and then will you use LVM to take another LVM > >> snapshot for it? If not how did you treat this qcow2 internal snapshot > later? > > > > No. Our VMs can have multiple disks on different storages. So we > > either use qmp commands to create internal snapshots (qcow2), or > > external tools - that depends on storage type. > > > > Basically we do: > > > > 1.) save state > > 2.) pause VM > > 3.) use qmp commands to create internal snapshots for all disks which > > supports that > > 4.) use external tools to create snapshots for other disks (nexenta, > > btrfs, ...) > > 5.) resume the VM > > > > Is that more clear now? > > > > Thanks for declaration, one more question: > 3) will have a big image file, will you back up it or just leave it there, not > backup for internal snapshot?
Sorry, I do not understand that question. Why will I have a 'a big image file', and what do you mean by 'backup' exactly?