Differential Backups

As far as I know, you should be fine removing backups as you describe. Just make sure you remove them all from one point forward. For example: If 10 is the last one to keep, delete 11 and all following images. When TI looks at the set, it will see 10 as the last one and continue from there.

Hello Mick,

MudCrab is correct, you can remove latest images (11-15) without any issues.

Thanks,

I hear what you guys are saying above, but I have a few questions, comments.

Why would you want to delete the latest differential backups (11 - 15)? This is the latest data, already backup up. If deleting it, you have no backup for the latest data? I would think deleting 1 -10 would be better. The 15th differential backup should contain all data changed or added since the last Full Backup.

I've been doing backups with various programs for 25 years, and Acronis Differential Backups seem backward somehow. I used differential backups often, and they worked list this?

For example: I make a Full Backup on August 1.

On August 10 I make a Differential Backup. This backup should include all data changed or added since August 1.

On August 20 I make another Differential Backup. This backup should include all data changed or added since the last Full backup (August 1). Therefore, the August 10 differential backup should not be needed anymore. Only ONE differential backup should be needed, including all data changed or added since the last full backup.

Acronis does not do this. I tried deleting some in-between differential backups. Acronis won't allow this, wanting to delete all of the later ones.

So I gave up on Differential Backups and do only Full backups. If I wanted a list of backups I may as well have used Incremental backups.

Ted

Ted wrote:

 

Why would you want to delete the latest differential backups (11 - 15)? This is the latest data, already backup up. If deleting it, you have no backup for the latest data? I would think deleting 1 -10 would be better. The 15th differential backup should contain all data changed or added since the last Full Backup.

i wondered the exact same thing.  what i concluded was that you just have to consolidate the earlier ones.  that's almost like the same thing.  although in that case the full backup would contain all the changes backed up in differentials 1-10, which you may not desire.  i dunno, i just started doing this making backup images deal a couple of days ago, so i'm still a pretty big noob.

Is Ted right about how differentials work?

What are advantages/disadvantages of diff/incremental backups?

Hmmmm, this is my first post.  There is a Save button and Preview button, but no Post button.   I guess Save means Post. So, here it goes.

Will someone please answer Ted's question?

Specifically:

"Why would you want to delete the latest differential backups (11 - 15)? This is the latest data, already backup up. If deleting it, you have no backup for the latest data? I would think deleting 1 -10 would be better. The 15th differential backup should contain all data changed or added since the last Full Backup."

Ted makes a very good point.  It's easy to see why someone would want to delete differential backups 1-10.  They are old, and as time goes, by the need to restore the system to an older point becomes less of a concern.  However, if I select differential backup number 11 for deletion, Acronis deletes 11-15.  This seems crazy. 

I see why this may be necessary for incremental backups.  Incremental backups are like links in a chain.   The most recent one depends on the one that immediately precedes it.  However, this is not so with differential backups.  One needs only the latest backup and the last full backup.  It seems that one would want to routinely delete outdated differentials and always save the most recent.

What are we missing?

Regards.

I am using True Image Home 2010 and the differential backups do work for me as described in article 1536 found here: http://forum.acronis.com/content/1536. This article also explains what happens when you delete a differential backup.

Once a full backup is created, each differential backup contains all the files changed since that full backup. So, every backup between the full one and the latest differential can be deleted. The deleting is best done through the Acronis program, Recovery page, right click the differential backup, Remove.

You will then be left with the full backup and the last differential, containing all the files that were changed since the full backup.

Of course, you may wish to retain some or all of the differentials to allow you to restore files to what they were on the date of the differential backup even though they were later changed again.

If your setup doesn't work the way article 1536 says it should, that suggests a problem that should be raised with Acronis. I hope this helps.

Hello all,

I understand the question and will do everything possible from my side to give you a clear explanation.

Greg the software shouldn’t suggest you to delete all subsequent differential backup archives in the chain the way you have described. So if you choose 10’h differential backup it normally shouldn’t delete backups from 10-15. As workaround you can delete 10’h differential backup archive manually, don’t use the program.

Ray the answer to your question is written in this KB article.

Let me know if you need further assistance.

Thank you.

I think Ted has it right, with the possible exception of number of differential backups. With incremental backup you need to keep the progression but with diff's you only need to keep the last good on and the image. If that is not correct will someone please explain.