Before installing FreeNAS® you should be aware of the following known caveats and issues:
- UPGRADES FROM FREENAS® 0.7x ARE UNSUPPORTED. The system has no way to import configuration settings from 0.7x versions of FreeNAS®, meaning that you will have to manually recreate your configuration. However, you should be able to import supported FreeNAS® 0.7x volumes.
- The ZFS upgrade procedure is non-reversible. Do not upgrade your ZFS version unless you are absolutely sure that you will never want to go back to the previous version. There is no reversing a ZFS pool upgrade, and there is no way for a system with an older version of ZFS to access pools that have been upgraded.
- The available space reported in the parent zpool may not reflect reality and can be confusing because the available space represented by datasets or zvols can exceed that of the parent zpool.
- Disks with certain configs can get probed by GEOM and become essentially unwritable without manual intervention. For instance, if you use disks that previously had a gmirror on them, the system may pick that up and the disks will be unavailable until the existing gmirror is stopped and destroyed.
- The mps driver for 6G LSI SAS HBAs is version 16, which requires phase 16 firmware on the controller. Running older firmware can cause many woes, including the failure to probe all of the attached disks, which can lead to degraded or unavailable arrays.