If you try to mount an ext3 Linux filesystem on a SAN from multiple nodes at the same time you will be in serious deep trouble.
SAN based storage allows multiple nodes to connect to same devices at the same time. Ext3/2 are not cluster aware file system. They can lead to a disaster such as kernel panic, server hang, corruption etc.
You need to use something which supports:
- Useful in clusters for moderate scale out and shared SAN volumes
- Symmetrical Parallel Cluster File System, Journaled
- POSIX access controls
Both GFS (RedHat Global File System) and Lustre (a scalable, secure, robust, highly available cluster file system) can be used with SAN based storage allows multiple nodes to connect to same devices at the same time.
Many newbie get confused as Linux offers a number of file systems. This paper (Linux File System Primer) discusses these file systems, why there are so many, and which ones are the best to use for which workloads and data.