On Sat, Jan 23, 2010 at 11:12:54AM +0100, Dirk H. Schulz wrote: > Ray Van Dolson schrieb: >> On Wed, Jan 20, 2010 at 06:14:02AM -0800, Dirk H. Schulz wrote: >> >>> 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? >>> >>> Dirk >>> >> >> I would think the best way would be to actually pause the VM. If you >> snapshot a VM while it's running, even with the above, how can you >> guarantee an application won't do something on the VM right as the >> snapshot occurs? >> > > That is an important point, I am already pondering about it. Of course > pausing the vm is the better option - if you can afford it. > > I am working systematically on an environment where the possibility of > very high level availability vms is part of the design (e.g. 99,99 %). > At the moment the only approach I can see is doing snapshots of a > running vm and making those as reliable as possible. > Pausing the VM doesn't really help. It doesn't guarangee in any way that the applications (say MySQL) are in a safe/consistent state. You really need to coordinate the process with the applications, if you realy need/want to make consistent backups with snapshots. -- Pasi -- Linux-cluster mailing list Linux-cluster@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/linux-cluster
