Repairing a Damaged ZFS Configuration
ZFS maintains a cache of active pools and their configuration on the root
file system. If this file is corrupted or somehow becomes out of
sync with what is stored on disk, the pool can no longer be
opened. ZFS tries to avoid this situation, though arbitrary corruption is always possible
given the qualities of the underlying file system and storage. This situation typically results
in a pool disappearing from the system when it should otherwise be available.
This situation can also manifest itself as a partial configuration that is missing
an unknown number of top-level virtual devices. In either case, the configuration can
be recovered by exporting the pool (if it is visible at all), and
re-importing it.
For more information about importing and exporting pools, see Migrating ZFS Storage Pools.