Hi John,
the Add-In WHS Disk Management may help you to determine the disk by its serial number (although it may be not as easy to figure out the serial numbers on the disks while mounted in the case, and if the same drive is shown as part of the storage pool and again as separate entity as I understand your description, this could also result in no serial number shown for the fake non storage drive).
As kariya mentioned, running chkdsk on each drive on the server would be a recommended option (but take a long time for this amount of disks). This FAQ explains, how to run it on all server drives.
Without an additional disk a controlled removal of the disk from storage pool (after identifiying) may be impossible, but if you disconnect if, bot drives should disappear (one claimed as missing in the storage pool) and you should be able to force a removal. Still have to recover the data, which may be unique on the disk.
If you have a spare USB disk, you could try to add this temporary to the storage pool, remove the faulty disk from storage pool, recover data, if necessary, fix or replace it and add the fixed/replaced disk again. After that remove the USB drive from the storage pool again, since the experience too often did show issues with USB drives integrated in storage pool.
Best greetings from Germany (Mecklenburg-Vorpommern)
Olaf
