Library based Tape license is the license for Tape drives. SSO is just for sharing the drives with other media servers. The drives themselves need to be licensed for use with Veritas Netbackup.
> What exactly is this for? We've got tape libraries > working with SSO and don't appear to need this so > what exactly is this license for?
Library Base Tape Drives license is require if netbackup is to be configured to use with tape library. SSO license is needed when one requires sharing drive device(s) among media servers.
The thing is we use a Storagetek SL500 library; the LBT license isn't installed on any of the servers connected to the tape library and it works fine. SSO I understand.
I should porbably mention we have NBU6 in case this makes a difference.