Originally posted by movva_uma
Why it needs a dedicated server process?
Because RMAN tipically will issue commands that will run for minutes if not for hours - it would monopolize the shared server if connected through a dispatcher, so preventing other users from using it; since the number of shared server is normally "low" (say, 20) and very busy, monopolizing even only one (but probably RMAN uses more than one of them) may impact the throughput seriously.
It would be like having a time-sharing system without preemption (the shared servers act like the cpus in this analogy).
Mts works well if the commands are short in duration and interleaved with "long" periods of inactivity, which is normally the case but not for MTS and e.g. Advanced Queueing.