Better ZFS pool fault handling coming to an opensolaris release near you!
I just saw the following ARC case fly by, and this will be a welcome addition to the ZFS file system!:
OVERVIEW:
Uncooperative or deceptive hardware, combined with power
failures or sudden lack of access to devices, can result in
zpools without redundancy being non-importable. ZFS'
copy-on-write and Merkle tree properties will sometimes allow
us to recover from these problems. Only ad-hoc means currently
exist to take advantage of this recoverability. This proposal
aims to rectify that short-coming.
PROPOSED SOLUTION:
This fast-track proposes two new command line flags each for
the 'zpool clear' and 'zpool import' sub-commands.
Both sub-commands will now accept a '-F' recovery mode flag.
When specified, a determination is made if discarding the last
few transactions performed in an unopenable or non-importable
pool will return the pool to an usable state. If so, the
transactions are irreversibly discarded, and the pool
imported. If the pool is usable or already imported and this
flag is specified, the flag is ignored and no transactions are
discarded.
Both sub-commands will now also accept a '-n' flag. This flag
is only meaningful in conjunction with the '-F' flag. When
specified, an attempt is made to see if discarding transactions
will return the pool to a usable state, but no transactions are
actually discarded.
I have encountered errors where this feature would have been handy, and will be stoked when this feature is available in Solaris 10 / Solaris next.
