Hi Bryn, On Tue, 17 Apr 2007, Bryn M. Reeves wrote: > > Assuming a dedicated VLAN which servers only AOE and GFS traffic among > > the Coraid boxes and the GFS hosts, is there any need for fencing at all? > > > > What are the hidden traps behind such setups? > > > > Best regards, > > Jozsef > > If you are using GFS on shared storage then you need fencing. Period. > > The only way you can guarantee data integrity in this scenario is by > completely cutting a failed or misbehaving node off from the storage; > either by power cycling it or having the storage reject its access. > > Otherwise, imagine a situation where a node hangs for some reason and is > ejected from the cluster. At this point none of its locks for the shared > data are valid anymore. Some time later, the node recovers from the hang > and begins flushing writes to the storage -> corruption. I see - the sentences above make much more clearer why fencing is needed. Thank you the explanation - and the hint for the possibility to reject the access at the storage itself! Best regards, Jozsef -- E-mail : kadlec@xxxxxxxxxxxxxxx, kadlec@xxxxxxxxxxxxxxxxx PGP key: http://www.kfki.hu/~kadlec/pgp_public_key.txt Address: KFKI Research Institute for Particle and Nuclear Physics H-1525 Budapest 114, POB. 49, Hungary -- Linux-cluster mailing list Linux-cluster@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/linux-cluster
