Solved my disk problem. I’ve got EVMS installed. Vaguely remember playing with it a couple of months ago and probably haven’t rebooted since. Changed the mount point in /etc/fstab from /dev/hdb1 to /dev/evms/hdb1 and all is now well.
The strange thing was that I could see the partitions on the disk using fdisk -l /dev/hdb and I could fsck the drive. I just couldn’t mount the partition.
Off to the gym.