I wouldn't do this at the SAS level, but at the software level. Most backup software supports storing data remotely; what you want is to do something like:
- Have a backup server that's connected to your tape library
- On that backup server, run some software that will schedule backups and write the data to tape
- On each server that needs to be backed up, run an agent that will send the to-be-backed-up data to the backup server.
SAS multi-host communication like that doesn't work very well, and also isn't necessary.
As for an example of a particular piece of software, I have had good experiences running backups to a bacula server, as well as its fork, BareOS. Both support backing up Windows as well as Unix systems, although the backup server itself needs to run some form of Unix.