We are running many Linux VM's in a vmware/shared storage environment, each running its own instance of postgreSQL (a mix of 9.0 and 9.3). Currently, the entire VM sits on a single root partition/volume, and we've had great success (~8 years) using storage-based snapshots of the underlying VMFS volumes for backup/restore process (and replication to our DR site).
Due to the architecture of our storage, it would be advantageous to separate postgres WAL files to a non-cached, mostly-write volume to …