On Sun, May 15, 2011 at 1:16 PM, Fred van Zwieten <fvzwieten@xxxxxxxxx> wrote: > Background: > NetApp Snashot functionality gives you application consistent > snapshots of data. Just inform the app a snapshot is about to be made, > depending on the app, it needs to go in to some sort of backup mode, > of just stop and flush outstanding I/O. Next, a snapshot is made and > everything just runs on. Because of the underlying WAFL filesystem > design, the snapshot always points to the blocks at the time of the > creation without needing to do any COW. > > Layered on top op this functionality is SnapMirror, where the delta > between this snapshot and a previous snapshot (both being static in > nature), is asynchronously replicated to a second system. There, this > delta is applied to a copy of the disk as a local snapshot. > > This setup gives you application consistent data disks on a remote > location as a form of disaster tolerancy. The RPO is the > snapshot/snapmirror frequency. > > KVM: > My question is rather simple. Could something like this be implemented > with kvm-img and rsync and/or lvm? I've played with the backing_file > option, but this means I have to shutdown the vm a boot is on the new > file to let this work. This recent thread might interest you: http://lists.gnu.org/archive/html/qemu-devel/2011-05/msg00733.html Basically you have to cobble it together yourself at the moment but there is activity around live snapshots and dirty block tracking, so hopefully they will be available as APIs in the future. Stefan -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
