Logical libraries are a way of taking your tape library and partioning it into different libraries….. Although, our 120 slot TS3310 is used as one library. It has 6 different tape drives, so this makes it easy run multiple backups and restores at the same time if we wish…. OR we could dedicate all 6 drives for a single backup. The data is spread amoung several tapes which does allow for a faster backup and restore. You can also have an ‘on-line’ copy of the data, where you store a set of data on tape that would stay in the the library and then an ‘off-site’ copy to tapes that you would pull out each day. We also have a 3rd backup that backs up to disk…. the fastest save and restore method possible. We are using the IBM TSM (Tivoli Storage Manager) for this.