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November 8, 2007

tips

Out of space? Try getting out of Time.

Posted Nov. 8, ’07, 9:07 AM PT by Dan Moren
Category | Tips

Time Machine prefThe mechanics behind Leopard’s Time Machine are pretty clever, despite forgoing the traditional route of flux capaciting. Through the use of hard links and file comparisons, Time Machine can save space by not updating files that haven’t changed, while at the same time maintaining the complete contents of your drive over multiple backups. Since big files like videos don’t change much, it only has to back them up once, but it’ll still appear in every backup, make it easy to navigate.

However, one problem with this methodology involves disk images, particularly if you use .Mac’s iDisk service. If you keep a local copy of your iDisk synced to your Mac, OS X makes a disk image of the iDisk’s contents. But since all of your iDisk files are contained in that single image, a change to any one of them means that Time Machine has to backup the entire image again—and with .Mac’s increase in storage, that means 10GB of files repeatedly eaten away from your backup drive.

An anonymous user at Mac OS X Hints suggests adding your iDisk image to Time Machine’s list of excluded files, arguing that the iDisk is, by its nature, already backed up on Apple’s servers. To do so, go into the Time Machine pane of System Preferences and click on Options. Hit the plus button, and you’ll be prompted to navigate to the files you want to exclude. Your iDisk image is kept in ~/Library/FileSync; you can exclude either that entire directory or just the image file you find in there.


3 Comments

Bob said:

Same thing goes for people using VMWare's Fusion and Parallels, doesn't it? All of the WinXP (or whatever) stuff is in one file. Even if you just boot up the guest OS and then quit you're going to get another copy of that 4, 5, 6 or more gigabyte file...and there is no backup of that like there is for an iDisk. They need to allow you to set a limit or something for those kinds of files, like 'only save the last 5 changes'. I guess none of the TM programmers used things like Fusion or Parallels.

November 8, 2007 10:34 AM
Jeff said:

Great advice. I tried this and was unsuccessful. I tried clicking on idisk and it wouldn't let me exclude it. I also when to Library as was mentioned in the posting, but I didn't see a filesync folder in there. Any suggestions?

November 8, 2007 1:20 PM
Dan Moren Author Profile Page said:

@Jeff: Make sure you're in your user Library folder: /Users//Library, not the root-level /Library folder. Also, remember that it only applies if you're syncing your iDisk with your Mac.

November 8, 2007 1:30 PM

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