TI10 Deleting Diff Files

This is unclear in the manuals. Regarding deleting differential backups files.

Example situation. I have a full backup followed by 8 differentials, made on the 8 days subsequent to the full backup. Today's file is number 8. I assume it is safe to delete differential files 1 through 7, inclusive, because if I have the original full backup and the 8th (or most recent) differential, then I can restore completely to the time the 8th differential was made.

Am I right?

 

You're absolutely right.
You need to keep files 1 to 7 only if you make incremential backups.

When you make an incremential backup, his origin is the last incremential backup.
Original <- day1 <- day2 <- day3 ...
(<- = needs)

When you make an differential backup, his origin is the original backup.
Original <- day1
Original <- day2
Original <- day3
...

 

Not exactly correct.

I have found that if, for example, there is a base, full backup and more than one differential backups off that base, then, if diffs earlier than the most recent one are deleted, T10 will not be able to validate the backups. It errors out, as follows:

1-Make Base backup 0
2-Take diffs 1, 2, 3 ... n
3-Diffs 1, 2, 3 ... n-1 are deleted
4-Run validation
5-T10 validates diff n then looks for diff n-1
6-Diff n-1 has been deleted and validation fails

The expected behavior would be that T10 successfully validates only the set (0, n) and does not attempt to validate the set (0, 1, 2, 3, ..., n), but that is not the way T10 behaves.

It would appear the workaround is to not delete diffs until a new base is taken, if validation matters to the user.

korm

 

This is known behaviour, and has been around since V9. The fact that Acronis have not sorted it implies that it is due to a fundamental design flaw, possibly resulting from some of the differential processing being based on incremental processing.

F.

 

It is a serious flaw. Serious enough that I intend to stop using the product and migrate to one that actually works as advertised.

korm