DPM 2012 Update Rollup 3 with 2x HP LTO5 drives in a Quantum i500 library, FC connected.
I have attached a screenshot showing the timing of tape backups involving SQL databases.
Notice that irrespective of size, the total time taken is at least 3 or 4 minutes. I have highlighted three examples where there is a trival amount of data involved (eg 3MB), yet DPM still spends over 4 minutes writing it to tape.
I'm starting to wonder whether DPM has a bug and is rewinding the tape after each database.
The same system backs up exchange databases (admittedly much larger at 500GB+ each) and streams at 80 to 120MB/s so raw performance isn't a problem.
The problem appears most noticeable on SQL databases, since many databases (master, model etc) are very small.
The actual databases all end up on the same two tapes (one tape per drive).
Any ideas?