For my company, TSM has been great. We have a UNIX/Linux, Novell, NT and NT w/ exchange environment with over 100 clients at our Corporate office. We replaced Legato NetWorker with TSM at our Corporate office last year. We had two Legato Servers, but now just one TSM server. The main difference so far has been reliability and shorter backup window (w/ Legato it took two days with two Legato Servers to do a full backup on all of the clients, where as TSM does incremental forever so we do not need to do anymore full backups). As for reliability, TSM has successfully backed up all of our UNIX/Linux and Novell clients for over a year now every night. It has also successfully backed up our NT boxes as well when they are functioning (periodically the NT boxes need to be rebooted.. not related to TSM).
The only problems with TSM is this product is no cookie cutter. You have to know how to set it up which takes a lot of reading and experimenting with. Once you understand TSM and setting it up for your environment, you are extemely confident in your backups.
- David Johnson