On Wed, Jan 20, 2010 at 03:14:02PM +0100, Dirk H. Schulz wrote: > Pasi Kärkkäinen schrieb: >> 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. >> > That means calling sync > echo 3 > /proc/sys/vm/drop_caches > inside the VM, right? Or is there anything more to do to flush everything? > And before those commands stop any databases or complex applications.. or make them flush their buffers and lock the tables for writes. -- Pasi -- Linux-cluster mailing list Linux-cluster@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/linux-cluster
