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Level 1

8 points

what does time machine backup?

Just wondering what time machine actually backs up? Does it do my entire system (so when I restore from a backup it gets everything from the backup) or just my files (and gets the rest of the OS and system files from an installer somewhere? In other words, if I want to perform a clean install of OS X, if I then restored from a Time Machine backup, would I have a nice new OS with my personal files on it, or would I have an exact clone of what I had before (including old preference and system files)??

Also, say if I installed Mountain Lion onto a blank drive, can I restore my files from a Time Machine backup of Lion during the setup process?

MacBook, Mac OS X (10.7.4)

Posted on Jul 27, 2012 10:24 PM

Best reply

Linc Davis

Level 10

209,547 points

Posted on Jul 28, 2012 11:10 AM

TM backs up everything on all internal drives by default, except some cache and log files. It doesn't automatically back up external drives. Restoring from a TM snapshot gets you a complete bootable system with all data, except as noted.

View in context

18 replies

Oct 12, 2015 9:17 AM in response to BobHarris

No. I am viewing one of the dated folders directly on the backup drive (e.g.. Backups.backupdb > my mac's name > 2015-10-12-XXXXX) and looking at the list of files shown in any of those folders.

BobHarris

Level 9

53,225 points

Oct 12, 2015 10:14 AM in response to VortexBoy

VortexBoy wrote:

No. I am viewing one of the dated folders directly on the backup drive (e.g.. Backups.backupdb > my mac's name > 2015-10-12-XXXXX) and looking at the list of files shown in any of those folders.

Most of those will be links to older snapshots.

The links are Unix hardlinks. If an entire subdirectory tree is identical, then just the subdirectory will be hardlinked into the older snapshot and will appear as if the entire tree is dupicated. If it is just a file that is identical in a directory of changed files, then just the file will have a hardlink to the older snapshot.

See this Time Machine FAQ

<http://pondini.org/TM/FAQ.html>

Oct 12, 2015 6:09 PM in response to BobHarris

OK, thanks for explaining that.

what does time machine backup?