I have used TSM (or ADSM or Spectrum Protect or whatever IBM calls it this week) quite a bit. The basic functionality and performance are not too bad. However, it clearly shows that the software originates in the 1980s. The client is written in C++ and really likes to leak memory. This becomes problematic when backing up more than a few million files. The official "fix" suggested by IBM is to configure a cronjob that restarts the scheduler once a day (seriously).
TSM also has no support for deduplication, so good luck backing up large variable binary files such as VM images or project files (video, CAD, etc).
I’m pretty sure it did originate in the 80s, it had an earlier name than ADSM, then was rebranded back when IBM was going to split itself into “baby blues”, then Lou Gerstner took over and stopped the split-up. Despite its faults it’s still the best I’ve ever encountered.
TSM also has no support for deduplication, so good luck backing up large variable binary files such as VM images or project files (video, CAD, etc).