One of my challenges is finding that optimum balance between "number of days retention" and size of "dedicated drive for backup only"
For what it is worth, I still think it would be very handy to select destination: "Local Storage" --> Destination Storage Device
then choose either:
1) Specify days to retain
2) Or, Select "Let VEB manage space"
Set it and forget it. Let VEB retain as many days as the designated backup destination can store.
Day 0 = 40 GB free... Full Backup (10 GB size)... 30 GB Free
Day 1 = 30 GB Free... Increm Backup (2 GB size) ... 28 GB Free
... [example with increm backups = 2 GB size each day]
Day 11 = 10 GB Free... Increm Backup (2 GB size)... 8 GB Free
... [some arbiturary process to conclude "too low on free space" ergo time to roll up oldest increm backup file]...
day 12 = 15 GB Free... Increm Backup (2 GB size)... 13 GB Free
Perhaps VEB/VSS there is a way to estimate size of backup before failure due to lack of free space?
(else some kind of less elegant formula filesize = multiple of the average increm backup file size.)