Merging iTunes across Time Machine images

December 2, 2012 9:02 AM

Once I had backed my iTunes up using Time Machine, I deleted some music on my computer to free up space. I've since added new music, which Time Machine has also backed up, but in discrete images. Is there a way to create a "master" library with exactly one copy of every song across all my Time Machine images?

In case you need a longer example, let's say I never listened to Murmur so I deleted it from my "live" iTunes. Since that happened, I acquired Life's Rich Pageant. No one Time Machine backup has both Murmur and Life's Rich Pageant in it, but I want to ("effortlessly") create a new repository of music that contains both albums.

I can't seem to come up with the right combination of keywords to find the answer to this on Google or AskMe, so apologies in advance if this turns out to be a redundant question.

(NB: I actually listen to Murmur all the time.)

posted by blueshammer to computers & internet (5 answers total)

I think Time Machine will eventually delete things that don't really exist on the hard drive that you're backing up. It's meant to be a backup, a copy, of your hard drive, not external storage. It will keep making new incremental backups, and when it's full, it'll delete the old ones.

The only way I know of to do what you're asking is to go back into Time Machine and "rescue" the old file (make it current) and then you'll probably need to re-import it to your iTunes Library.
posted by brentajones at 9:50 AM on December 2, 2012

That is how Time Machine behaves, but I've been backing things up into a sufficiently capacious volume that this was not a worry. I can go and individually "rescue" things, buuut ....
posted by blueshammer at 10:07 AM on December 2, 2012

Yep, if you need more space, the thing to do is buy an additional disk. You can partition (divide) the disk that has the Time Machine on it, but then you'll be relying on a single physical disk to backup itself, which is risky.

I don't know of a way to automate what you're asking for.
posted by wnissen at 10:11 AM on December 2, 2012

What about a good way to do a comparison so I at least know which folders to rescue from which images?
posted by blueshammer at 10:57 AM on December 2, 2012

Well, you can mount the TimeMachine backups through Finder, and each backup is in its own dated folder. So, you should be able to use any number of available File/Folder Comparison utilities to compare the differences between different snapshots: 'diff' on the command-line to DeltaWalker. I doubt you could run an automated merge across an arbitrary number of folders (backups). The pro version of DeltaWalker does support a 3-way comparison, but that is probably the best you can hope for.
posted by insert.witticism.here at 1:23 PM on December 2, 2012