How Time Machine might work

"Bare" with you?!?! What do you think this is... Nudevine?!

Aside from the obscenity, great analysis of how Time Machine might work. It seems like a very interesting method of backing up data and I'd love to see if your predictions are true.

Time machine seems to be one of the most promising new technologies of the next computers, but one thing has me off balance. This is the second application apple has created that abandons their old GUI and takes up the full screen. Could this be a sign of whats next, an os that abandons all the things that oses have today, and works more like the menus on a 360?

Time Machine is definitely the most interesting thing on Leopard (that we know of) but I agree with you that there are a lot of questions that will eventually need answering.
Looking forward to seeing it in action.

I think you can use the use some of the features without a external hard drive, I beleave it can use the local hardrive to backup deleted files if you want it to, so you can go back in time to get it back. But I may be wrong.

I too am wondering how Time Machine will work. Backing up an entire system would obviously require a ton a storage space. I don't want my internal drive capacity to get chewed up, but I also don't want to have to buy an external drive. It will be interesting to to see there solution.
I'm not too worried about the lag during the keynote, at best it is in an early Alpha so they've got plenty of time to optimize it.

It's either a local or an external hard drive, but no mention of DVD backup (as that doesn't really work well or even at all with versioning, which is what Time Machine does).

So it's essentially Apple's own, internally developed CVS system?

Damn, I was hoping for crazy discussions of temporal paradoxes, relativity, quantum mechanics, tachyons, and assorted other interesting time travel based fun.....not backup software! Damn you apple!

Nice article though :D

From the sneak peak website:

Time Machine works great out of the box, but you can customize it by modifying the following behaviors in System Preferences:

• Backup Disk: Change the drive or volume you're backing up to. Or back up to a Mac OS X server computer.
• Do Not Backup: By default, Time Machine backs up your entire system. But you can also select items you'd rather not back up.
• Backup Time: Time Machine will back up every night at midnight, unless you select a different time from this menu.

There's your

system preference where you can define exceptions such as "files over 4GB" or "files with extension mp3", etc.

Sorry for the double post, but I just thought of this.

I wonder if you could even backup to another partition on the same drive. Obviously, this wouldn't do anything for a drive failure, but it would still work for the "OMG WHERE'S MY PRESENTATION?!" syndrome they were promoting it for.

Oh! One more thing... did you notice in the keynote whenever Time Machine was activated, it would stutter for a few milliseconds? They launched Safari, Mail and iPhoto like it was nothing and Time Machine visually hung for just a moment. That worries me.
When things are slow in a keynote, they're usually painstakingly slow on your Apple Hardware.

I'd think that this is due to the fact that Time Machine's not completely finished yet. It's a completely new application, unlike Safari, Mail and iPhoto, so it's likely that the team still has a few things to clean up before the final release. At least I hope that's the case.

I'm not sure how accurate your predictions are going to be, from what I've read.

1. I've read nothing about "local" browsing without the external drive, and my guess would be that maintaining a mirror of the Time Machine files database on your main HDD wouldn't be included. After all, if you look at some of the screenshots, they include icons, specifically custom picture icons, that would take up more space on the local drive. My guess is that if you launch the application without your backup drive mounted, that it will throw an error and ask you to mount it. (Or a more elegant solution.)
2. I would also imagine that maintaining daily backups without the backup drive would simply not happen. (See Faruk's comment on old revisions.) I imagine that backups will only occur when the backup drive is mounted. In other words, you're SOL on the road.
3. The DVD issue has already been discussed, though would be nice.
4. The key point on your "rip, burn, delete" example is that Time Machine backs up at a specific time every night (like midnight). So doing work during the day won't cause any huge files to be backed up. This is a good reason to set your backup time to something obscure, like 4:00 am.

And one more response...

If this is being targeted to smallish documents, presentations and the like, it would make sense that compression would be used. Anything that's predominantly text can usually be compressed fairly quickly, and often to less than 10% of its original size. That would certainly help in this scenario.

However, we know for a fact that Apple's also targeting "priceless digital photos, music, [and] movies" (source). I'm not sure if compression would be used, especially seeing how Time Machine works by showing you the exact contents of a folder one right after another. That would be a lot of decompression to a temp folder, deletetion, rinse, repeat.