When I set the option to have a max of "3" full sets and to DELETE BEFORE the backups starts, all seems to go as planned.
BUT it seems that the CALCULATION for the amount of disk space require for the backup happens BEFORE the deletion. This means that if my backup drive is running low of space, the backup will FAIL and tell me I don't have enough space EVEN THOUGH I would have enough space if the MR program would just continue and do the deletion of the old full backup and then do the normal backup job.
Get what I am saying? IE: The calculation function should "in my opinion" happen AFTER the deletion process. OR at least take into account the size of the old backup sets and subtract that from the total space required for the backup. Makes sense to me, hope it does for you as well ;)