With multiple tape drives and automated tape handling, tape libraries provide a lot of functionality for enterprise backup. However that functionality comes at a price and when selecting a tape library it makes sense to get one that will give you expandability.
To help insure expandability there are several features to look for when choosing a tape library. For example the library should have the capacity to add more tape drives if needed. This will let the library's performance expand to fill the ever-shrinking backup window. Adding a new drive is a lot cheaper than buying a new library.
Another important feature is barcode scanning. While you can manage a few tapes without barcodes, as the number of tapes grows barcode will help you -- and the library -- keep the tapes straight.
The library should also be easy to expand in the field. If the service tech has to take the library back to the shop -- or ship it back to the factory -- you're going to be without your backup for a while and that's not a good thing.
Qualstar discusses selecting a tape library in a white paper titled "Tape libraries for lights out operations".
Rick Cook has been writing about mass storage since the days when the term meant an 80K floppy disk. The computers he learned on used ferrite cores and magnetic drums. For the last twenty years he has been a freelance writer specializing in storage and other computer issues.