How to remove phantom pool that lives on detached USB?

[guermantes]

So...my partner pulled the power cord for an external USB drive that was currently imported to FN 11.2-U3 for offsite backup purposes. Backup script had long since finished, so I don't think it was in the middle of reading/writing. But of course the pool became UNAVAIL. Stupid me tried to export the pool to get rid of it, thinking freenas would default to remove the pool from zfs memory if it couldn't be found. But instead the GUI just hang and the spinner never went away. After waiting a long while I decided to reboot from the GUI. Seemed to work at first since my SSH session I also had open was immediately closed. But nothing more happened, it would not reboot. So I went into IPMI and saw the console message: init: some processes could not finish, ps axl advised. Only I could not issue that command anywhere since the SSH option was no longer possible, and the IPMI console was not accepting input (weird, I remember having sent keyboard strokes before via the remote HTML5 console). So I risked it and issued restart from the IPMI menu instead. That worked.

Now the system is online. The USB drive still has no power and after boot the USB drive pool is UNKNOWN. I guess I should tell zfs to forget about it before I re-import to do a scrub. But how do I best do that?

The GUI does not seems to offer an option, or at least I don't want to try export/discard another time without having been instructed to do so since it did not go well the last time. Should I do something at the command line? Or is my best option to simply reattach the USB drive and hope that it and the pool are well received by zfs?

 

[guermantes]

Okay...no immediate answer so I guess the question was stupid. I switched on the USB drive and risked a restart of Freenas and the unknown pool popped into place. Now onto the scrub...