I have an external WD 1TB drive that was a time machine backup device. It was corrupted yesterday by Mavericks and the drive is now lost. Neither Drive Genius or Diskwarrior or Disk Utility could recover it. FWIW.
ugh..I have a couple of WD externals, so I think I'll hold off on going to Mavericks until I hear more about this. Maybe the issue is only the WD provided software - I would never use the software provided by the drive maker; stick to osx disk utility to partition/modify.