On Thu, 2005-06-30 at 11:27 -0400, Andrew Forgue wrote: > Nate Carlson wrote: > > > On Thu, 30 Jun 2005, Patrick Caulfield wrote: > > > >> Not really. The whole point of the quorum is to prevent > >> "split-brains" where two nodes can see the shared storage but not > >> each other - which would corrupt the filesystem because they can't > >> co-ordinate locking. > > > > This reminds me, how does a cluster behave that has an On-disk quorum > (Tru64 and Windows, off the top of my head)? In those OS'es you have to > dedicate a partition for "quorum". Are there any advantages to this, or > am I just misunderstanding something. Disk based quorum algorithms (with appropriate fencing) can be used to do N -> 1 failover (e.g. operation with only one node). They can also be used to prevent split-brain cases in a more scalable fashion (giving you 50% votes being okay instead of 51% - this could allow a 4-node cluster to operate with 2 nodes online, for example). Of course, now you have to have good shared storage in order for your cluster to work at all, which isn't a requirement of CMAN or GULM currently. -- Lon -- Linux-cluster@xxxxxxxxxx http://www.redhat.com/mailman/listinfo/linux-cluster
