Take the 2-minute tour ×
Super User is a question and answer site for computer enthusiasts and power users. It's 100% free, no registration required.

I have win 7 scheduled to backup every Sunday, it's only looking at one of my drives at the moment and is backing up to an external HDD. It's a 1TB drive so should take quite a while to fill but the amount of time the backup takes makes me think its taking a fresh copy every time.

It's now 21:34 and I think backup started at about 19:30. It did a full backup earlier in the week of approx 200GB. Is it copying the whole lot again? Or is it just taking its time checking for differences?

share|improve this question

1 Answer 1

up vote 21 down vote accepted

Windows 7 Backup is a block based file backup.

This means each block in a file is examined and if a duplicate already exists on the last backup, and this is the important bit, even if from a different file, that block is not saved. Quite good :)

The first backup is always a full backup. The following backups will only save changed blocks. Disadvantage is you cannot manage your backups individually.

share|improve this answer
    
ah! Very clever. So the time delay is due to re-examining all the blocks. Do you have a link to some futher reading on this? –  G-. Oct 25 '09 at 22:07
    
ermm.. will have to search for that. Been a while since I last read about it. Will add a comment with the information –  A Dwarf Oct 25 '09 at 22:18
5  
Incremental here: social.technet.microsoft.com/Forums/en/windowsbackup/thread/… Block based incremental here: social.technet.microsoft.com/Forums/en/w7itprogeneral/thread/… There's somewhere, on one of the developers blogs or something, a detailed explanation of the Backup features. That's where I remember reading about it the first time during the beta times. I just can't locate it right now. But those two links should be enough. –  A Dwarf Oct 25 '09 at 22:29
    
Excellent, thanks –  G-. Oct 26 '09 at 20:17
2  
So... If you deleted something prior to the last backup (therfore blcks have changed) does that file get removed from the backup image as well? –  user50272 Jan 8 '11 at 5:23

protected by slhck Apr 20 at 7:47

Thank you for your interest in this question. Because it has attracted low-quality answers, posting an answer now requires 10 reputation on this site.

Would you like to answer one of these unanswered questions instead?

Not the answer you're looking for? Browse other questions tagged or ask your own question.