Billy Newport, one of the architects and developers of WebSphere Appication Server, has a blog: /dev/websphere. It's a really good resource that explains some of the more interesting new developments in the WAS products, as told by one of the guys who helped put those features in there. I've added it to this blogs list of blogs that I need to be keeping up with (a.k.a. "Blogs I read," in the right-hand column).
Case in point: Billy just posted WebSphere 6.0 and NFS V4/SAN FS, a match in heaven. Of course! Huh?
Basically, he explains how the transaction manager in WAS 6 provides rapid (i.e. about 12 seconds) recovery of in-doubt transactions. That means that if your Web site crashes, even if a customer that was in the middle of placing a bizillion dollar order and successfully committed the transaction, the order won't be lost; his work will failover to another WAS server in the cluster and will take a fraction of a minute to recover, as if nothing happened. That's pretty quick recovery, and it's automatic. Furthermore, such an arrangement usually requires some pretty fancy (and expensive) storage hardware such as a SAN or a disk array, but WAS 6 does it with the disks on any standard file server.
Check out Billy's blog to learn more.
WebSphere 6.0 high availability with shared file systems