I'm really looking for something that will cluster the filesystem across multiple nodes for both enhanced performance and redundancy, sort of RAID 1+0 over TCP. There is already a Windows DFS "cluster" on-site that does this (hence the questions about Samba - I'm not sure whether the MS Unix Services will serve a DFS and I'd trust Samba over Microsoft's implementation of NFS), but I'd rather have a linux-only setup for Moodle ( ).
DRBD wasn't ideal as IMO it "wastes" a node when the cluster is fully operational; since Intermezzo isn't ready for production use, I'm thinking of giving PVFS (Parallel Virtual File System Version 2) a go which seems to do this and more, unless you can provide any more good ideas
Thanks everyone for all the help!
BTW The Performance pages in the Moodle wiki are still lacking on the topic of clustering...