I encountered a bug in ZFS where the zfs range lock and file locking had some trouble. Result was a blocked jvm that was not resolvable and finally blocks access to /proc. You could start processes but had no access using proc tools (no view, no kill etc.) You had to reset the machine.
The OS was 10u9 where the hassle started with a patch day involving about 130 patches back in 2011 . One of them was not that good.
So be careful. I had the trouble with 3.3.5 and 3.4.x
The best way to check if your system is stable is a full re-index of a large data store and a full re-sync with your ldap ( ~ 10000 users should be enough). The bug may come with high frequency read/write cycles.
Good luck.
Torsten