Cannot mount external USB drive

Question

During a recent update I remember pacman asking about replacing some package with another package to handle disk mounting.  I think the added package was "gnome-volume-manager" or "gnome-disk-utility" (or both).  I didn't see any postings describing problems with doing this, so went ahead and allowed the change.  Now it's a few days later and I find I cannot mount an external USB hard drive anymore.  It has an entry in fstab, and although I have tried mutiple edits of the device to associate the drive with, nothing works. 
The disk used to associate with /dev/sdb1.  Now this device no longer exists.  Here is what has happened to my /dev/sd* entries:
brw-rw---- 1 root disk    8,  0 2009-10-27 11:08 /dev/sda
brw-rw---- 1 root disk    8,  3 2009-10-27 11:08 /dev/sda3
brw-rw---- 1 root disk    8,  1 2009-10-27 11:08 /dev/sda1
brw-rw---- 1 root disk    8,  2 2009-10-27 11:08 /dev/sda2
brw-rw---- 1 root disk    8,  4 2009-10-27 11:08 /dev/sda4
brw-rw---- 1 root storage 8, 16 2009-11-04 13:00 /dev/sdb
Trying to force association with "/dev/sdb"  "/dev/sda5" (or some other number not in use) or "sdb1" (or 2,3,4, whatever)  just yields "special device ... does not exist".
Does anybody know how to deal with this?
Does anybody know what package(s) I replaced when the update in question took place?  I think I'd like to reverse whatever happened.
And on another note, I think another gnome-based package also recently replaced a package relating to printing.  Yesterday I discovered I have printing problems too:
At first there were no printers found.  Although cups is supposed to start according to rc.conf, cupsd was not running.  I started it manually and then all the printers showed up again, though I cannot print duplex (again, worked fine before).  What is going on with these gnome packages?!?  Anyone know which package(s) I need to remove (and then what to put back) to make printing work like it used to also?
thanks much.

Answer 1

oddly, fdisk -l shows nothing, even for disks which are mounted (eg. /dev/sda4).  when I insert a standard USB thumb drive, the following show up properly:
brw-rw---- 1 root storage 8, 32 2009-11-05 10:50 /dev/sdc
brw-rw---- 1 root storage 8, 33 2009-11-05 10:50 /dev/sdc1
and I am able to mount and use the drive as usual.
The external drive I've been struggling with has xfs for filesystem type.  After using the thumb drive, /dev/sdb showed up spontaneously, but no /dev/sdb1.  attempting to mount gives:
mount: /dev/sdb is not a valid block device 
or
mount: special device /dev/sdb1 does not exist
depending on which device is specified in fstab.
I am thinking that either a) my ability to mount xfs filesystems has somehow been hosed, or b) there is something wrong with drive, which must have spontaneously failed very recently (it is less than 1 yr old, but this happens from time to time).
If the drive is okay, any ideas about how mounting xfs filesystems could have been broken by recent upgrades?
btw, the fstab entry (which worked fine until a couple days ago) is:  /dev/sdb1 /mnt/external_1 xfs rw,noauto,user,exec 0 0