I recently updated my mac pro from Mavericks to Yosemite. Afterwords my ZFS raid 5 stopped working (was not seen by the system). Please read this entire guide and the warnings before trying to fix your issue! Also please backup your data before trying to fix your zfs raid.
To fix this I did the following:
Next i upgraded my zpool from Terminal
After all this i noticed the mount point for my zpool was not set so i set the mount point.
To verify the above command worked i displayed the mount points
After this i saw that it was not mounted so to mount the pool you do
After this I was able to use my raid 5 drive.