[OpenIndiana-discuss] Destroying unavailable ZFS dataset

[Jan Owoc]

Hi Michelle,

On Sat, Jun 1, 2013 at 12:13 PM, Michelle Knight <michelle at msknight.com> wrote:
> The system contained two SSD drives for the OI OS, mirrored.
>
> The data was kept on a zfs pool called "data" - (yeh, original, I know)
> - which consisted of three WD green drives.  These were previously
>   2TB's and were later upgraded to 3TBs
>
[...]
>
> However, with FreeNAS installed on a USB key and the old SSD stripped
> of partitions and installed as a jail partition, when I use ... zfs
> import ... (the new 3tbs are not installed at this point) ... it still
> shows the old "data" zfs set and of course, being unavailable because
> none of the old drives are present.
>
> I am concluding that something on the old SSD drive still has a record
> of the old ZFS set which must have been stored somewhere other than the
> standard partitions ... I don't know where else this information could
> have come from.

Yes, this is indeed odd that information about the pool "data" would
be stored on the SSDs.

I'm not sure if it's an option, but these two posts [1],[2] seem to
think that overwriting the first and last bit of the drive (eg. 2MB)
should overwrite the ZFS header information. Is this an option, or
does the SSD have important data on it currently?

[1] http://techarcana.net/2009/02/19/stubbornly-persistent-zfs-pools/
[2] http://forums.freebsd.org/showthread.php?t=29739

Cheers,
Jan