I'm in the process of migrating our cluster to new hardware. We use bare metal servers, no virtualization.
Currently, we have around 30 "application" servers. When we make an update, we push the changes to one machine, then use lsync (a branch of rsync) to push the new files to all of the machines in the cluster.
My new idea was to use a SAN along with iscsi to simply "share" the app across all servers from one location. Little did I know that you can't really do that out of the box. Each machine slices out its own piece of the SAN, but the machines can't see each others files.
What is the best way around this? We're running Centos 6.4 on all of the machines. I stumbled across this, but have heard mixed things about running a clustered filesystem http://ricardobaylon.wordpress.com/2013/11/11/centos-6-4-cluster-gfs-iscsi/