Running SLES 11 SP2 with latest patches (as of 15/7/2013), SLES HAE SP2 OCFS2 Version 1.6_3.0.13, XEN
5 Node Cluster OCFS2 gets broken by the latest kernel update.

All other SLES nodes running kernel 3.0.58
Updated one server to kernel 3.0.80 and ocfs2 will no longer mount

Code:
ocfs2 Internal logic failure while trying to join the group
Jul 15 12:48:44 sl-bne-hs23-01 kernel: [ 3496.524201] (mount.ocfs2,21615,11):o2hb_map_slot_data:1638 ERROR: status = -12
Jul 15 12:48:44 sl-bne-hs23-01 kernel: [ 3496.524208] (mount.ocfs2,21615,11):o2hb_region_dev_write:1768 ERROR: status = -12
By back rev'ing the kernel to 3.0.58, the system starts up again with no problems, ocfs2 mounts coming up correctly
Version 3.0.74 was not tested due to the need to get a live system back on line. No other patches had to be downgraded on the 5th server. Just the kernel-xen and the kernel-xen-base

This kernel version has been marked protected on our SLES cluster servers until a resolution is found.
Thanks
Eric