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giulio 11-16-2007 09:25 AM

How does Time Machine work?
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When Time Machine does a backup, is it recopying everything all over again? See this view:

So is Finder being slick and showing the restored size, or is each backup really 10GB?
That is a 500GB drive. There are 13 backups, each over 10GB. But there is 453GB remaining. So only 47 GB were actually used (well actually a lot less because a 500GB is really only about 480GB usable or somthing like that).

Any idea?

RiDE 11-16-2007 09:37 AM

I think the Restore as of 6:16am today is 10.92gb. Finder is showing how large each Restore would have been. The backups are taking up 11.08gb of space, as you can still Restore to 12:41am if you wanted.

giulio 11-16-2007 10:45 AM


But what if large files are in one BU and deleted in a next? This is confusing to me. How do we find out the actual backup sizes?

Dillinger-63 11-16-2007 10:48 AM

I tried to save some space on my external so I thought I would delete a few of the oldest back-ups, BIG MISTAKE. Apparently the first back-up made cannot be deleted or it messes up all the others. Anyway, I'll just reformat my external and start from scratch with Time Machine.

goobimama 11-16-2007 10:52 AM

Those multiple files are actually the same data. Time machine saves the same files over again, but just the hard link, the data is the same. It's better explained on Appleinsider in the excellent article:

Road to Leopard: Time Machine -

giulio 11-16-2007 11:46 AM

Oh it makes hard links? Thats why the file sizes display as they do... very cool.

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