GlusterFS is *not* a block-capable product. It's file only. IMHO it's also about the slowest for mixed data. And I'd not trust any really valuable data to anything other than RedHat's supported version (RedHat Storage Server).
For filesystems, you've got many more choices, including BeeGFS, MooseFS, RozoFS and more (OSS or semi-open development model) or Exablox, Isilon, Hitachi, HP StoreAll (proprietary).