General non specific question on Disk Imaging.

Years ago when I first started using Acronis (back in Vista days), I always understood that once you restored a disk image from a set of either incrementals or differentials, that if you then attempted to carry on adding new backups to that existing chain that the next incremental or differential would be massive in size because pretty much everything had changed.

That made sense, like moving all the books on a shelf left or right. Nothing has changed and yet in a way everything has.

I seem to remember discovering that the hard way by seeing how the next incremental made after restoring an image was almost the same size as the base image.

Yesterday I tried this again (using AOMEI) and am amazed to see that the next incremental is of a normal small size. Because I knew I would need to do a restore (I wanted a play with some Windows stuff that would break things) I deliberately made a single full backup to restore from.

Today I thought I would try and add to the incremental chain I had already in place... result, a normal small file size.

Do all modern backup programs now behave like this ?

Hi Mooly,

Does Aomei use its internal catalog? Does Aomei run from Windows? If yes, system restore may include restoring of Aomei itself & its catalog created before, that is why it continues to work in chain of previous diff/incr backups.

(Only my thought, I do not use it.)

Yes, it will run from within Windows. That is how it use it 99% of the time.

Incremental backup can use two approaches to build list of files to backup:

1. File attribute Archive (the standard approach): it is set by operating system if file is created or changed and cleared by backup software if file is a part of either full or incremental backup (not differential). But in the time of restoring file, backup software can either leave the OS to set the attribute of restored (= created) file or clear it itself, so the size of next incremental backup may be dependent on used software.

2. Date & time of file creation/change: backup software should set original timestamp while restoring file but some software may behave differently; in this case OS sets new timestamp of restored files and next incremental backup will be much bigger.

In addition, both approaches can be influenced by internal catalog of files which backup software makes. So the "best practice" is: After system restore, the first following backup should be Full, which starts new Incremental chain.

Thanks for the info on that. I don't know what protocols AOMEI actually uses, I was more just surprised it could pick up as if nothing had happened when continuing with a backup sequence.

Normally I would always do you as you recommend and start a new sequence off... but I just got curious on this and wanted to see what happened.

Thanks :)

You're welcome, Mooly. Unfortunately, I don't use Aomei so I can't give you more accurate info.