A week or two ago I heard second hand about someone saying "they can't use Galera because they use SAN for everything". Well, just so there is no doubt: You can perfectly well use Galera together with SAN. Galera is quite agnostic about the disks used.
In fact, Galera might be a great option together with SAN. Often SAN means slightly worse latency for disk writes, in particular when used with iSCSI. If the network path to the SAN is poor, it might mean a big performance hit, actually. Galera is in fact a good fit here, because the default/recommended setting for a Galera cluster is to relax the durability settings for InnoDB (innodb_flush_log_at_trx_commit), since durability is primarily guaranteed by the syncrhonous nature of the replication. (Same philosophy as is applied in the architecture for MySQL NDB Cluster.) This reduced stress on the disk can actually improve your experience with a SAN. A case in point is running Galera in the Amazon cloud with EBS volumes, we constantly get very good performance results in that environment compared to the competition.