'Clearing' zpool.cache

[PM]

Hello,

ages ago I had an zpool (USB disk) for temporary usage (backup).
Cannot remember if I had 'removed' it properly, the disk
is also long ago gone (physicaly!) but still present in
'/etc/zfs/zpool.cache' (after many updates/reboots/power-off-on's)
and thus zpool still complaining:

$ zpool status
...
pool: usbback
state: UNAVAIL
status: One or more devices could not be opened. There are insufficient
replicas for the pool to continue functioning.
action: Attach the missing device and online it using 'zpool online'.
see: http://www.sun.com/msg/ZFS-8000-3C
scan: none requested
config:

NAME STATE READ WRITE CKSUM
usbback UNAVAIL 0 0 0 insufficient replicas
c11t0d0s2 UNAVAIL 0 0 0 cannot open

'action' is not an option for me (no disk!), so how to clear this
'information' from zpool.cache?

Thank you,
PM

[PM]

Never mind, found a/the solution (from Cindy and Casper):

http://comments.gmane.org/gmane.os.solaris.opensolaris.zfs/45153