Differential backups are taken as the difference between the current state, and the last full backup called the "differential base".
Does restoring a full backup reset the differential base? If so, is there a way to avoid that?
The Microsoft docs only say that a backup resets the differential base. My experiments are a little inconclusive, although it seems that restores also reset this value.
I have a list of full backups taken sequentially over time. I'm switching this to a periodic full backup, with interspersed differential backups, eg. one full backup a month, with hourly differentials. However, the existing backup sets are all full backups.
I'm writing a script I want to run on a spare server which will go through the existing sets and sequentially restore them and generate differentials from the backup at the beginning of the month. This won't work if a restore resets the differential base though.
Any pointers or suggestions would be much appreciated. I actually already had something like this working with a binary diff program, but that mysteriously broke this month, so I'm trying to switch to using the built-in differential backups.
Edit: gbn as adequately answered the question of whether the restore resets the differential base, but I'd still like some suggestions on whether it's possible to extract a differential backup if given two full backups.