Thanks for the response so quickly.
I did a quick test for a job per server. It used both drives at the same time.
Look like the advantage for this might be utilized my 2 drives units and cut short of my backup time needed for Weekly backup (23hours).
The disadvantage for this is takes more tapes to run this unless I set the overwrite protection to long number. But there is more for that!
This is my idea (BTW, no more new tapes no budget): suggestion are welcome!
Daily still run as one big job, 4 of my servers can run just one tape per 6 days – 4 tapes per month.
Weekly will cut down to 2 servers per job. I think this is call load balance (hope it works).
This will take up to 4 tapes daily/month and 16 tapes (Sorry! LTO4) for a month of weekly data.
Schedule the Studio Test backup away from the Infrastructure backup hours (night).
Well, more test to do before I can safely say it save time and data.
One little story, our backup was on backup to USB Drive and take 24 + hours per server (600G).
And catalog a drive will take up 9+ hours for a size of 750G USB drive (got that to retrieve one deleted file).
The new Robotic Libraries is almost heaven (but also nightmare just all by myself plus so many other my part-time job :D)