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Differential Backup

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Hi

Please correct me if I recall this incorrectly and even after reading thread KB1536.
Differential backups only backup what has changed since the last full backup .. correct.
I.e File A in Folder 1 is backed up on monday using Full backup. On Tuesday a differential backup is run on Folder 1. File A hasn't changed but File B has been created. The backup should only contain File B and not A as it has not changed

If I am correct why oh why is Acronis TIH 2012 backing up everything again and again when no changes have been made.

I am trying to backup my BluRay/DVD Rips which are about 2TB. I run a full backup first and then run differential backups but even tho nothing normally changes it tries to backup the whole 2TB again..

Chris

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Acronis does not look at files to do backups, it looks at blocks of data (or sectors), if any data is changed on a particuler block/sector then that block/sector is backed up. If there is no change to the block/sector it is skipped. If your drive/partition that has the DVD rips is highly fragmented and/or has large numbers of blocks/sectors of free space spread throughout the drive/partition and you rip a new DVD to the drive, the block/sectors that are empty will be written to, and parts of the files could be spread all over the disk/partition. Acronis would then see the changes in the blocks/sectors and back them up again. Also if you have auto defragmentation setup, you should turn it off. Anytime Windows performs a defragmentation on a drive, many data blocks/sectors will be changed, although no data has been updated. Since DVD files are already highly compressed, you may want to use a utlity that syncs folders and set that up to provide a backup of the rips instead of using Acronis to backup the drive/partition that contains them.

Thanks James F. Does it do this even using File backup? I can understand it doing that on a disk/partition backup.

Regards

Chris

A differential backup contains all the changes since the last full.
An incremental backup contains only the changes from the last inc.

If full run Sunday, and diff s made daily, the diff run on Thursday would contain all the changes since the last full on Sunday. The Thursday file would be chosen for restore and the restore would be made of Sunday Full and Thursday Diff. After the restore, the computer would look as it did after Thursday backup.

As opposed to Inc.

If full on Sunday, and inc made daily, the inc run on Thursday would only contain the changes since Wednesday. In order to get the computer to be the same as it was when the Thursday inc take, the restore would require the restore of the backups from Sun, Mon, Tue, Wed, Thu. with the Thursday Inc being the file chosen for restore.

Is the Do not delete the first version of the backup option enabled for the backup task? That would result in two Full images before the Differentials would start.

@GroverH I know about differential and incremental backups as I use to run server backups. However the issue I was having is that using Acronis TIH 2012 a differential backup (using file backup not disk pr partition) is still backing up data that hadn't changed. As you can see from James F he says that acronis looks at sectors so therefore doesnt seem to matter whether diff or increm as anything and everything is probably changing the sector.

@MudCrab Where abouts is that setting as I cannot see it to check what its on.

That option is in the scheme settings for Full backups in the automatic cleanup section. You shouldn't see it if doing Incrementals or Differentials. However, tasks sometimes get screwed up. Have you tried recreating the backup task?

Are you running a Full backup and then trying to run a Differential? Normally, you'd just set the scheme to Differential and it will create a Full automatically on the first backup.

What happens on the third backup run? Does it also try to create a Full?

Does the log state that a Differential was created or does it say it was a Full?