One more clarification. As long as I only put partitions from the same node into a RAID set, the corruption shouldn't happen, right? lin > -----Original Message----- > From: linux-cluster-bounces@xxxxxxxxxx > [mailto:linux-cluster-bounces@xxxxxxxxxx] On Behalf Of Lon Hohberger > Sent: Wednesday, December 06, 2006 7:45 AM > To: linux clustering > Subject: Re: Software RAID support by GFS > > On Wed, 2006-12-06 at 09:57 -0500, Josef Whiter wrote: > > Hello, > > > > Software RAID has the same limitation as LVM1 as it's not cluster > > aware. Even with LVM2 you have to use CLVM to make sure the > > appropriate cluster wide locking takes place before touching the > > metadata on the disk. Software RAID has no cluster > awareness, so you > > could run into the same problem you would have if you > mounted an ext3 > > filesystem RW between two nodes, you would end up with corruption. > > This isn't a limitation with GFS, but more a limitation > with md RAID, > > as its not cluster aware. Thank you, > > > > I *think* this is because write ordering between parts of a > md-raid set isn't guaranteed... I've actually forgotten how > the corruption occurs. > (d'oh!) > > e.g. Two guys write to the same md-block at the same time. > One writes in {1 2 3 4 5} order, the other writes in reverse > order - the stripe for that block is now corrupt. > > ... not to mention cache-coherency problems with md-raid. > > -- Lon > -- Linux-cluster mailing list Linux-cluster@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/linux-cluster
