There are now 4 tapes in the pool.
1 for Monday, 1 for Tuesday, 1 for Wednesday and 1 for Thursday.
As there is enough space on the tape, I want to use 2 backup cycles per tape. (retention period of 13 days)
So every Monday, the Monday tape is inserted.
after a job, the tape is written for about 25%
But for example, if the accidentally insert the Wednesday tape, instead of the Thursday, the backup is still possible to run, because there is free space available on the tape.