Hi Thomas
(BTW, I'm not seeing anything from 'Thomas Kloeber' across on zfs-discuss..)

Ok, so it looks like I identified things the wrong way around.
So maybe the size of the usb disk appeared to increase when
you moved it from the Ultra25 to the PC.

I'm not sure how the ZFS code works out where to look for labels (2,3)
(Need to look at the code, when I have some spare time.)
I would speculate it somehow works out the size of the disk
and then offsets from that value. So either way, if the size of the disk
increases or decreases, it would not find the labels 
in the 'correct' place, and fault the pool.

Over on zfs-discuss, we had a similar problem:
http://www.opensolaris.org/jive/thread.jspa?threadID=79749

Ok, so from 'prtvtoc /dev/rdsk/c5t0d0s0', we have

  16065 * 60801 = 976,768,065 sectors

..so thats 500,105,249,280 bytes.

(The other thing I would like to understand, is how the zdb value
for 'asize' relates to the true size of the disk.
>From what I've seen, asize is always a little smaller than disk size.
Again, I would need to look at the code, when I have some spare time.)

Ok, so when you had the usb drive on the PC, you somehow seem
to have created a new pool called 'WD'. 

I would speculate that's very unfortunate, as it may well have overwritten
other vital data, related to the original pool 'usbdisk',
such as the uberblock.

(Your zdb output does not seem to have a uberblock section.
Maybe that's a newer feature of zdb, and not in the older Solaris 10 zdb.)

Now you have the usb drive back in the original Ultra25, the 
usb disk appears to be slightly smaller in size, compared to when it was
on the PC, and  back to it's original size.

Let me try a ASCII diagram to illustrate my idea.
Labels (0,1) have been overwritten, and the 'WD' labels (2,3)
are off the end of the disk, but it can now see the original
'usbdisk' labels (2,3), as they are found back in their original position.

Ultra25 - |0|1|----------|2|3|   (Pool 'usbdisk')

     PC - |0|1|------------------|2|3|  (Pool 'WD')

So I think that would explain the labels we see from, 'zdb -l'.
Regards
Nigel Smith
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