"Normal" backup backs up too much

[arnstein]

Using Retrospect 7.7.325, Windows XP. Up to date with respect to Windows Update. My backup media are external (USB) disk drives.

 

Last night, Retrospect backed up many gigabytes of files more than necessary. I looked through the backup session log in Retrospect. There are files on the backup media that have not been modified since 1998. This, acccording to Retrospect itself. Why did Retrospect copy these old files to backup media?

 

Recently, I turned on the backup option "Media Verification" for all of my backup scripts. Then, I updated Retrospect to version .325. Perhaps these changes are relevant. However, I have only observed the problem on one backup medium (external disk drive) so far.

 

How can I prevent (or at least diagnose) this excessive use of backup media?

[rxlaw]

Welcome to the fun and unpredictable world of Retrospect's incremental logic. But it is a major PIA due to the time to do that first backup (all files), and more importantly, it starts appending to your existing backup set, essentially doubling the media requirements.

 

I've had this happen twice, with each version update. For some reason, Retrospect seems to not recognize the previous snapshots and which files have not changed.

 

Never got a good explanation, but if it happens once every couple of years, I guess it's tolerable.

 

Bob.