Brian, ----- "Brian J. Murrell" <[email protected]> wrote:
> On Wed, 2009-03-04 at 17:03 +0000, Daire Byrne wrote: > > > > Once you move to LVM then you can snapshot the MDT and mount that without > > unmounting the production MDT. You should probably destroy the snapshot > > afterwards as it affects performance somewhat. > > And just to be absolutely clear for those who don't realize, as the > number of snapshots of a single device increases so does the > performance penalty. > > There is another snapshot technology at http://zumastor.org/ that > claims to efficiently store snapshots to as not to suffer the same problems. > I have yet to find the time to evaluate it though. I looked at zumastor. Although it didn't get any slower with extra snapshots it took quite a hit (~ x6 drop in writes) with just a single snapshot. It was also a bit buggy and I didn't particularly like the userspace<->kernel interface. Far more promising is the port of zumastor exceptions to the kernel and the work being done to add a generic shared exception store interface to device-mapper (and ultimately LVM): https://www.redhat.com/archives/dm-devel/2009-February/msg00014.html It is a Redhat effort so it might actually be useful one day. Daire _______________________________________________ Lustre-discuss mailing list [email protected] http://lists.lustre.org/mailman/listinfo/lustre-discuss
