Thinking Different: Time Machine

Watching yesterday’s Steve Jobs keynote at WWDC, the thing that really surprised me was Time Machine. Where has this been all my life? I am curious about some of the tech details. For instance, does it store diffs like CVS or only entire files? How do I securely delete something? Can I exclude large files I don’t want to back up to save space? (Update: Yes.) Can I specify redundant backups across multiple hard drives and network connections? Are the backups compressed? Can you backup to removable media? Is a .Mac subscription required? Will this backup system files or just home directories? (Update: Yes.) Will it create bootable backups? Do different file types require custom support, as with .Mac Sync? Can I back up network clients too? But overall these are only things a geek would think of and half of them only a geek would care about.

I wasn’t so impressed when I just heard about Time Machine, but when I actually saw it I was astonished. What surprised me was the user interface. This is decades beyond any other backup program I’ve ever seen. Once again, Apple threw out conventional thinking and designed something that’s actually easy to use. I don’t think other backup programs have changed in any significant way in the last 15 years. Why is only Apple able to think of things like this?

3 Responses to “Thinking Different: Time Machine”

  1. Poster Says:

    Many of your questions are answered at

    You should submit your unanswered questions to Apple, like the ones about secure delete and redundant backups.

  2. Matthew Wilson Says:

    “All features referenced in the Mac OS X Leopard Sneak Peek are subject to change.”


  3. Paul Says:

    You should check out Macworld’s in-depth look at Time Machine, which answers some of your questions:

    Here’s a sampling:

    “Behind the scenes, Time Machine’s doing a lot of clever things in order to create the impression of a seamless backup. The first time you run Time Machine, it copies the entire contents of your drive (cache files excepted) to the backup drive. After that first process, Time Machine only backs up files that have been added or modified.”

    “Just as Mac OS X notifies Spotlight when a file has been modified (so it can be re-indexed), Leopard will notify Time Machine of any changes to your Mac’s files. Every so often, Time Machine kicks into action and copies those changed files to your backup drive. At the end of the day, Time Machine coalesces all of those changes into a single collection of changes for the entire day, and adds it to a pile of days that extends as far back into history as your hard drive’s capacity will allow.”

    “What happens when your backup volume fills up? Apple says that Time Machine will give you a few options: First, you’ll be able to cull out extraneous or unimportant files that are taking up space on your backup drive. Second, it’ll offer to step you through the process of moving your files to a larger backup drive. And third, it’ll let you scale back the reach of Time Machine—for example, reducing your backup from a year to nine months in order to reclaim drive space.”

    “And what if the unthinkable happens and your drive crashes, losing all your data? Install a new hard drive, point Time Machine at your backup volume, and your Mac will reassemble your drive from the data on the backup volume using a file-transfer process similar to Apple’s Migration Assist.”

Leave a Reply