Suggestion for my backup plan?

Differential backs up every file changed since the last full. Uses more space than incremental but much faster and easier for restoration.

I use Acronis for my drive images. I don't create them all that often. I keep a fresh install with all my settings and programs and I'll periodically make one before large windows updates or if I am testing new software.

For my mirror and my differentials I have been using Cobian for many years. Cobian Backup

Incremental vs. differential backup: A comparison

Differential backup

Differential backups copy those files that have been changed since the last full backup took place. So if a full backup was done on Day 1, Day 2's differential will copy all of the files that have changed since Day 1's backup copied everything. Day 3's differential backup will also copy all of the files that have changed since Day 1's full copy was made.


Incremental backup

Incremental backups copy all of the files that have changed since the last backup was made. They do this whether the last backup was a full one or an incremental copy. So if a full backup was done on Day 1, Day 2's incremental will back up all of the files that have changed since Day 1. Likewise, Day 3's incremental backup will only copy those files that have changed since Day 2's incremental took place.

cyberSAR said:

Incremental vs. differential backup: A comparison

Differential backup

Differential backups copy those files that have been changed since the last full backup took place. So if a full backup was done on Day 1, Day 2's differential will copy all of the files that have changed since Day 1's backup copied everything. Day 3's differential backup will also copy all of the files that have changed since Day 1's full copy was made.


Incremental backup

Incremental backups copy all of the files that have changed since the last backup was made. They do this whether the last backup was a full one or an incremental copy. So if a full backup was done on Day 1, Day 2's incremental will back up all of the files that have changed since Day 1. Likewise, Day 3's incremental backup will only copy those files that have changed since Day 2's incremental took place.

For incremental backup, if Day 2's incremental is corrupted/missing, and if I want to restore data in Day 3's incremental backup I will not be able to restore correct?

For Differential backup, if Day 2's Differential is corrupted/missing, and if I want to restore data in Day 3's Differential backup I will be able to restore correct?

Thanks

Not necessarily. In incremental if day 2 is corrupted you lose those files (unless they were also backed up on day 3) but day 3 would be fine.

Look at it this way. If you do a full backup and 5 days of incrementals to restore you would restore the full backup then day 1, then day 2 then day 3 then day 4 and finally day 5.

In differentials you would restore the full backup then day 5. No need for days 1-4 as they are contained in day 5s backup.

hope that helps.

cyberSAR said:

Not necessarily. In incremental if day 2 is corrupted you lose those files (unless they were also backed up on day 3) but day 3 would be fine.

Look at it this way. If you do a full backup and 5 days of incrementals to restore you would restore the full backup then day 1, then day 2 then day 3 then day 4 and finally day 5.

QA) Do you mean if day 2 incremental file is corrupted, day 3, day 4, day 5 incremental backup can still be restored successfully?

QB) Incremental backup example: If on day 2 morning, I created a new file day2note.txt in my PC, at night when incremental backup happens, day 2 incremental did have the day2note.txt file inside. After some months, when I tried to restore the day2note.txt file in day 2 incremental and unfortunately day 2 incremental was somehow corrupted and unable to restore. Will restoring day 3 or day 4 or day 5 incremental backup be able to restore that day2note.txt successfully ?
Will day 3 or day 4 or day 5 incremental backup contain day2note.txt ?

Lady Fitzgerald said:

You are confusing incrementals with differentials. An incremental includes only data since the previous image, be it a full image or an incremental image. With incrementals, all copies have to be present and uncorrupted for full recovery. If day 2 is corrupt, you will only be able to restore with the initial full image and the first incremental. You will not be able to use day 2 and any day after that.

"If day 2 is corrupt, you will only be able to restore with the initial full image and the first incremental. You will not be able to use day 2 and any day after that." > I do think incremental backup works like this too,
but cyberSAR (thread #56) said: "Not necessarily. In incremental if day 2 is corrupted you lose those files (unless they were also backed up on day 3) but day 3 would be fine."

cyberSAR is wrong? (he said day 3 would be fine)