Question Macrium differential file smaller than incremental

[CrispyBytes]

Hi,
I am in the process of evaluating Macrium Reflect to backup my 500Gb SSD boot drive. The amount of used space on the drive is currently 330Gb.

I created a full backup on 26th August, then created a couple of test incrementals which I deleted (via the Macrium interface).

I have now set it to run an incremental at 6am and a differential at 7am each day, and will leave this testing for a few days. I've included a couple of pictures of the settings below.

I had expected that the first time the backup ran, the size of the incremental and the differential would be fairly similar, however, it turns out that the incremental is twice the size of the differential (14Gb v 6Gb).

As far as I can tell from the interface, the incremental and differential are both children of the full image (and not of the deleted incremental tests), so I can't understand why the incremental would be so much bigger than the differential, especially as it was imaged first (incremental at 6am, then differential at 7am).

The PC was not in use during the backup and the backup files are written to another physical disk.

Does anybody have any thoughts? Any input would be much appreciated.

 

[ss202sl]

An incremental backup will reset the archive bit where a differential will not. It's not a good idea to run both. The differential backs up everything that does not have the archive bit set, so it did not backup what the incremental backup did(because the incremental reset the archive bit).

 

[CrispyBytes]

Thanks.

So it is not a differential of the full backup at all, just a differential since the last backup (i.e. the incremental)?

I must be missing something because that doesn't seem to make sense. If a differential were just all of the changes since the last incremental, wouldn't it then be no different to just another incremental?

One of the template backup plans (Grandfather, Father, Son) is set for daily incremental, weekly differential and monthly full.

Isn't the whole point of the differential that it gives you all of the differences since the last full, so to restore you only need the full and the latest differential?

What is the point of the differential, if you still need all of the incrementals to restore?