there are some errors unmounting that is why you get a new device name when you reinsert the device.
Oct 11 20:59:57 vector vl-hot_umount: ERROR unmounting /mnt/vl-hot/sdd/vol
The user most likely ran a program that accessed files in the volume, or used the mount point or one of its subdirectories as its working directory, and then didn't shut it down. (Completely unrelated, but the OpenOffice Quickstart tray icon in Windows does or did something very similar. It's quite annoying.)