Time Machine Speculation

[Qion]

Well, how do you guys think it works?

Main problems I forsee:

1. What happens to those of us with laptops who enjoy disconnecting from external drives when we visit the café or generally move about? If you were to, per se, download an "I'm a Mac." commericial, watch it, and delete it 5 minutes later, would Time Machine still access it? Would Time Machine work at all?

2. What happens when you are continuously running Time Machine for months on end, and constantly create/delete large files? How would it ever begin to account for the film industry without having gigantic ammounts of storage to feed into?

3. If you were to, for whatever reason, disconnect from a volume, do a lot of work, and reconnect to that volume, would there be a large pause while Time Machine "automatically" updated?

My personal opinion is that Time Machine will somehow access "deleted" files from exactly where they were deleted. As some of us know, when you erase something, it doesn't actually go away until something else fills the same sector of space. This would run into problems, however, with conspiracy theorists and their zeroing and people who do not own 1TB hard disks.

I guess we're just stuck speculating...

(Oh, and on a completely unrelated tangent, why do you think Steve had two iSights connected to his computer(s)? Back-up system maybe?)

[Mikuro]

It seems that Time Machine will not log every little change. It's not a real-time thing like Spotlight. It's more like OS 9's indexing. From Apple's web site:

Backup Time: Time Machine will back up every night at midnight, unless you select a different time from this menu.

So, once a day (maybe more or less if you can specify it) it will back up all modified files. I doubt it deals with "ghost" space at all.

I really don't know how they're going to deal with large files like video. What happens when the backup disk fills up, as it will inevitably do? Are older backups silently removed to make room? Are new backups ceased? Does it cry like a baby and tell you to buy another HD?

[Satcomer]

The big things I see are still unanswered.

1) What if you don't want to use it, can it be turned off?
2) Will it work with more than just FireWire and USB2 drives? I mean things like raids, external off site servers and things along that line.
3) If someone has an external hard drive and another machine user or another machine access the data?
4) Will it make a boot able clone?
5) Will it back up immediately so if I delete some 10 minutes ago and get it back?
6) Will it only work with HFS+? Will it support other formats? Also will it work with my internal 4 hard drives (in the MacPro)?
7) Can two or more users use the same backup drive?

There are probably at least 50 more questions that others have. Also it looks like Apple is stepping on a lot of backup developers toes.

[powermac]

Those are great questions. When I read and seen the demonstration it reminded me a bit of my IBM Aptiva I had several years ago. The computer had a program where you could go back and restore files, etc. From what I understand the program only wrote what had changed, not everything. In other words, the system registered a changed in a particular file or folder, and those that had not changed where not written.
Not sure how Apple is working Time Machine. It does look like it will be a handy app.

[Ferdinand]

Time Machine IS the coolest Back-Up App (if thats what I can call it). Even though I dont have a copy of Leopard (I only watched the WWDC from the computer) I think it will blow the Backup app in the dust. Its much simpler than backing up. But: What if the Harddrive breakes, so the files arent accessable anymore. What will Timemachine do? It cant recover anything.

And... why are they bringing it out ONLY in Spring? Why not much eariler like November or October? If they announce it before christmas, then more people will buy it (as a Christmas present). Thats how they selled so many 5th gen iPods.

[Mikuro]

Originally Posted by Ferdinand

And... why are they bringing it out ONLY in Spring? Why not much eariler like November or October?

I'm guessing the same reason they didn't release it today or in January or the day after Tiger came out: it's not done yet. As long as they don't pull a Longhorn on us, I won't complain. Personally, I think it was silly of them to announce the name as soon as they did. All it did was get people thinking "Leopard! Leopard!", and now we've been waiting for it for so long (even though it was nothing but a name until Monday) Spring 2007 seems so...far...awayyyyy....

Two years between major releases isn't so bad. Most people feel abused with faster updates. ("They want me to pay again already?!")

1) What if you don't want to use it, can it be turned off?
2) Will it work with more than just FireWire and USB2 drives? I mean things like raids, external off site servers and things along that line.
3) If someone has an external hard drive and another machine user or another machine access the data?
4) Will it make a boot able clone?
5) Will it back up immediately so if I delete some 10 minutes ago and get it back?
6) Will it only work with HFS+? Will it support other formats? Also will it work with my internal 4 hard drives (in the MacPro)?
7) Can two or more users use the same backup drive?

My guesses:
1. Apple says "By default, Time Machine backs up your entire system. But you can also select items you’d rather not back up." I'm guessing this will have an interface similar to Spotlight.

2. Apple stresses "servers" a lot, both in Steve's keynote and the Time Machine page. The TM page only specifies machines running Mac OS X Server. It's hard to say whether servers based on other OSes will work.

3. The backups would probably have the same permissions as the original, in which case it would be the same as trying to access the original from another user/system. Any other way would seem kind of backwards, wouldn't it?

4. I've been wondering this myself. Apple hasn't offered any real clues. They say it will back up everything, but they don't really say anything about how it's stored. Booting from backed-up data would cause a lot of complications, though, since it would make the backup out of sync with the original (you can't boot without altering some system files and prefs and stuffs). So my instinct is "no", but I hope I'm wrong.

5. Apparently not. Apple's TM page says it's scheduled, and that by default it backs up every night at midnight. If it logged every little change, that would be impressive, but it would also fill up the backup disk like mad! I don't think anyone really wants to back up every single file that makes its way into their web browser's cache, for instance.

6. My guess is that you can only back up HFS+ drives (since it will probably use Spotlight to determine which files need to be backed up, and Spotlight only supports HFS+). Maybe you'll be able to use other formats for the backup volume, but I doubt it.

7. I would think so, since apparently it's made to use source drive as the backup. It would seem very strange if it TM was limited to just one user on isolated machines (which means the vast majority of consumers, probably).

Of course, it's all just speculation. Even what Apple has said directly is subject to change, as they remind us at the bottom of every page about Leopard.


Last week people were hoping Leopard would be released at MWSF in January. Now it seems more likely that we'll merely get all the details of Leopard in January.

[chevy]

On the sneak peeks on Apple web site, it looks like Time Machine is integrated in the applications, as if it was managing the applications' data base. If this is the case, this is completely different from a generic back-up software.

But it also only applies to compatible software.

[Mikuro]

All the data from those other apps would be stored in files, so it's possible apps like Address Book just poll Time Machine for the old files, and process those files the same way they process the current files.

But you could be right, and it could be much more sophisticated than that. It seems likely that it would at least make special considerations for the Spotlight database; after all, it would be silly to back up the entire database every day if only 1% of the entries in that database would be any different from the previous day. A Spotlight database could easily be hundreds of megabytes.

It's possible that Time Machine will use temporal compression, storing only what has changed in every day's entry, much the same way a modern video codec only stores what changes between frames. It would be quite a feat to make that work efficiently and flexibly, though. The Address Book test proves that Time Machine needs to be fast enough for programs to perform arbitrary analysis of the old data in close to real time, and any compression scheme would surely take its toll on performance.

I'm sure a lot of people at Apple lost a lot of sleep thinking about all these problems. I reeeeally want to know more about Time Machine's inner workings! But it's fun to speculate.