Thank you all. I fully appreciate the efforts and time all of you take to write follow-ups to my question.
But I need to clarify :
- Library to me is the JRiver database, otherwise I would say media files.
- I do not want to work directly on the main library (even through scope limited views).
- I do want the main library to be active all the time, so OTA-TV recordings and users are serviced as usual.
- I do backups of the main library almost daily.
- I have full backups of my photos and audio files.
- While the original blu-rays are available, I do not have pockets deep enough for a backup of my ripped movies (protected by Snapraid's RAID6 though).
- I will work on copies of the audio files, leaving the originals available to all users in the meanwhile.
- For me, the nicest machine to work on for that job is the aforementioned workstation/server.
- Whenever instance 2 (MC2x-SA2) is running, the original instance 1 (MC21-SC1) will only run media server, not the client part.
- I am not a newbie. I have been using JRiver since MC9.
- At worse, if all else fails, I could launch another MC21 in a Hyper-V virtual machine, but thought the problem is interesting.
Some of you, well meaning, present me alternate ways that I am already aware of.
I really want to run a second instance,
personally I have never done so, but ask if it is feasable to do so when the first is also serving media to other computers, and ask for potential pitfalls / previous experience.
It may be that I am the first to try this, and if I pursue that way will certainly follow up with what I found.
So, by all means, please keep the advices rolling, but within the bounds of my question