OCFS2 is a general purpose extent based shared disk cluster file
system with many similarities to ext3. It supports 64 bit inode
numbers, and has automatically extending metadata groups which may
also make it attractive for non-clustered use.

You'll want to install the ocfs2-tools package in order to at least
get "mount.ocfs2".

Project web page: http://oss.oracle.com/projects/ocfs2
Tools web page: http://oss.oracle.com/projects/ocfs2-tools
OCFS2 mailing lists: http://oss.oracle.com/projects/ocfs2/mailman/

Note: Features which OCFS2 does not support yet:
- extended attributes
- shared writeable mmap
- loopback is supported, but data written will not
be cluster coherent.
- quotas
- cluster aware flock
- Directory change notification (F_NOTIFY)
- Distributed Caching (F_SETLEASE/F_GETLEASE/break_lease)
- POSIX ACLs
- readpages / writepages (not user visible)

source code:

fs/ocfs2/