On Sun, Jan 17, 2010 at 02:47:00PM +0100, Dirk H. Schulz wrote: > Ray Van Dolson schrieb: > >>Hmm.. so snapshots with CLVM are possible nowadays? > > > >No.... > > > >RH has stated (recently on this list) that patches exist to do it, but > >it hasn't been a high enough priority for them to complete the work to > >the point where it could be distributed to customers. > > > > Okay then, how do you people out there with clusters that run virtual > machines with live migration do backups of the virtual machines? > I surely do not want to shut down the virtual machine to be able to copy > the image safely away if I have live migration available. > > At the moment there is only one way I can see. PLEASE prove me to be wrong. > Searching in RedHat's documentation I found that the problem is that lvm > snapshots need exclusively allocated logical volumes. So I think the > following > should be technically possible: > 0. Start environment: the logical volume containing the images of the > virtual machines uses gfs and is mounted on all relevant cluster nodes > since VMs are running on several cluster nodes. > 1. All VMs have to be migrated to one of the cluster nodes > 2. On all other nodes, the gfs volume is unmounted > 3. On the remaining node (where all VMs now run) the logical volume is > bound exclusively with "lvchange -aey LOGICALVOLUME" > (I hope this is possible without deactivating it first) > 4. Now GFS on this volume is frozen: "gfs_tool freeze > /mountpoint/of/local/volume" Before freezing the GFS you should make sure the VMs are in consistent state, and the VMs have flushed their caches/buffers/disks. > 5. Now the snapshot is generated and mounted > 6. GFS is unfrozen again > 7. The virtual machine images are copied off the snapshot > 8. The snapshot is umounted und undone > 9. The LV is activated on all cluster nodes again, GFS file system is > mounted on all relevant cluster nodes again. > 10. The virtual machines are migrated back to whereever they belong. > > Now I would like to know: > - is that basically the correct approach? > - is there any better method to backup the virtual machines without > shutting them down? > - is anyone out there using the above steps regularly in a production > environment? > -- Pasi -- Linux-cluster mailing list Linux-cluster@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/linux-cluster
