[Linux-cluster] Fencing agents

["Sævaldur Arnar Gunnarsson [Hugsmiðjan]"]

I'm implementing a shared storage between multiple (2 at the moment) 
Blade machines (Dell PowerEdge 1855) running RHEL4 ES connected to a EMC 
AX100 through FC.

The SAN has two FC ports so the need for a FC Switch has not yet come 
however we will add other Blades in the coming months.
The one thing I haven't got figured out with GFS and the Cluster-Suite 
is the whole idea about fencing.

We have a working setup using Centos rebuilds of the Cluster-Suite and 
GFS (http://rpm.karan.org/el4/csgfs/) which we are not planning to use 
in the final implementation where we plan to use the official GFS 
packages from Red Hat.
The fencing agents in that setup is manual fencing.

Both machines have the file system mounted and there appears to be no 
problems.

What does "automatic" fencing have to offer that the manual fencing lacks.
If we decide to buy the FC switch right away is it recomended that we 
buy one of the ones that have fencing agent available for the 
Cluster-Suite ?

If can't get our hands on supported FC switchs can we do fencing in 
another manner than throught a FC switch ?




-- 
Sævaldur Gunnarsson :: Hugsmiðjan