On Fri, Jan 15, 2010 at 01:35:14AM -0800, Pasi Kärkkäinen wrote: > On Thu, Jan 14, 2010 at 02:57:03PM -0500, Jeff Sturm wrote: > > > -----Original Message----- > > > From: linux-cluster-bounces@xxxxxxxxxx > > [mailto:linux-cluster-bounces@xxxxxxxxxx] > > > On Behalf Of Dirk H. Schulz > > > Sent: Thursday, January 14, 2010 12:21 PM > > > To: linux clustering > > > Subject: Snapshotting GFS and freezing > > > > > > Hi folks, > > > > > > I found several howtos on the web stating that if you want to snapshot > > a > > > gfs volume (on top of clvm, of course), you have to freeze gfs (using > > > gfs_tool) to make that possible. > > > > > > What comes in mind then is: If I have to freeze the gfs volume anyway, > > > do I need a snapshot at all? Can't I copy the contents off the frozen > > > gfs volume directly? > > > Because the basic purpose of a snapshot is to provide files that do > > not > > > change during beeing copied. And I would expect a frozen gfs volume to > > > provide exactly that. > > > > The important consideration here is: How long can you withstand the > > filesystem being frozen? > > > > You can freeze it, copy all files (e.g. with rsync) and unfreeze, > > potentially over the course of a few hours. If that's okay with your > > application and users, go right ahead. > > > > Or you can freeze, snapshot and unfreeze, and potentially be done within > > a few seconds. That's the beauty of snapshots--we do it online with > > little or no user disruption. > > > > 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. Ray -- Linux-cluster mailing list Linux-cluster@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/linux-cluster
