I have to say that TSM on Windows is good for small to medium size solutions and I'm not ANTI-Windows. I just cringe when dealing with devices in Windows. I hate its driver handling and most of all I hate how Windows presents library and tape drives. So I was working with a TSM server where the tape library would not initialize. It was an older SCSI library, not Fiber. I tried restarting the library, the TSM server, reloading drivers, and updating the drivers and nothing worked.
Duh! <Head Slap!!!>
That's because on the initial reboot that caused the library to stop communicating the device ID's changed. So the library went from LB184.108.40.206 to LB220.127.116.11. Nobody touched the SCSI card or library but the device definition changed! Seriously? All the drives changed to mtX.X.X.3 also. Now I don't use Windows all that much but luckily I remembered the TSMDLST program that is installed with the TSM server. It's under C:\Porgram Files\tivoli\tsm\console and will pull the information from Windows for you in a readable format. So next time your library goes offline make sure you use it to compare the device definitions and serials with what is defined in TSM. It will save you a lot of time and headache. You can find more information on issues like this here.