Another Time Machine problem (?): very limited backups

[absurdio]

So, during the Leopard development, I recall reading (sorry, I haven't got links now) that Time Machine wanted to use external hard drives the same size as the drive being backed up.
Now, whether that's accurate or not, that's what I've done; I've got a 160gb external hd to backup my 160gb mbp disk. But the backups only date back to yesterday (I installed Leopard perhaps a week ago). This seems intuitive enough, I guess (after all, how could Time Machine magically fit several iterations of your disk on a disk the same size as yours?), but the implications are troubling. Does that really mean that if i accidentally deleted a file two days ago, that it's gone forever? Does that mean I can only recover files that were lost a few hours ago? And isn't there a way to make Time Machine back up your machine, say, twice a day, instead of every hour?
I was just charmed by the idea of being able to go back months into history and recover lost files...but being able to travel back only a few hours in time has fairly limited utility value.
Also, my MBP hard drive is not full. It's still got nearly 30GB free. That's not enough that you could copy the drive onto a backup twice, but I'd still like to think Time Machine was capable of a bit better.
Is this normal? Is there a way to improve it?
Thanks.

 

[superleccy]

...that Time Machine wanted to use external hard drives the same size as the drive being backed up.

No. The time machine hard drive should be as big as possible. A good rule of thumb is twice the size of your internal HD, but you'll probably want something even bigger if you're constantly working with large files (eg, video). The bigger the external HD, the more history you get to keep

Is there a way to improve it?

Get a bigger external hard drive, or exclude a few large folders (eg, your iTunes library, if you have a big one).

Time machine may be cool and groovy (IMHO), but it can't magic external HD space out of nothing.

SL

 

[absurdio]

A good rule of thumb is twice the size of your internal HD, but you'll probably want something even bigger if you're constantly working with large files (eg, video). The bigger the external HD, the more history you get to keep

...Will a drive twice the size internal hd let you go back...two days in history, instead of just one? Maybe three, I guess. Still, I'm a little troubled by the thought that the things I'm backing up are only backed up for a couple of days, and if I don't notice a missing file within that time span, it's gone for good. Them's the breaks, I guess.

Get a bigger external hard drive, or exclude a few large folders (eg, your iTunes library, if you have a big one).

Sage advice; thank you. I have a second, larger hd, but it's busy. My iTunes library is quite large, though, and I've since instructed Time Machine to stop backing that up. That certainly ought to help.

Time machine may be cool and groovy (IMHO), but it can't magic external HD space out of nothing.

No, I didn't suppose it could. I thought, perhaps naively, that it'd be possible for Time Machine to just track changes, rather than recording a whole new iteration every time (that is; if the only thing that's changed between last week and this week is that a 10mb file was deleted, I guess I assumed Time Machine would be able to retain that 10mb file in its place in history, but not need another copy of all the other files that hadn't changed).
Anyhow, thanks for your help; if nothing else, I'll try to swap external HDs and repurpose the larger one for backups.

 

[superleccy]

When you start Time Machine for the first time, it copies your entire hard drive. Then on subsequent backups, it only copies new and modified files. When the TM HD gets full, it deletes its own backups, starting with the oldest.

So you had about 30Gb free on your main HD, so you should've had 30Gb free on your TM HD after the first backup, space which would have been used to backup subsequent iterations of individual files. Sounds like a lot, but it also sounds like TM managed to eat this pretty quickly. Perhaps you've been editing / working with large files (or lots of small ones).

I also think TM counts a file as "modified" if it is changed in any way whatsoever. Ie, files that are only part-modified, date-changed or just moved will all be backed up the next time TM runs.

An example: Like you, my main HD is 160Gb with 20-30Gb Free, but my TM HD is less than twice the size, at 300Gb. I installed Leopard on 30th November, and TM can see all the way back to then - and I still have 129Gb free on the TM HD! (I'm not excluding anything either). In that time, I've mainly been doing a load of audio editing. I guess I'd have a lot less space left on my TM drive if I'd been (say) video editing.

Another tip: If Time Machine backs something up that is taking up loads of space and you're 100% sure you never want to see it again, you can delete it (and all iterations of it) permanently from the TM drive. Highlight the file in TM, click the cog button and check out the delete options you are offered.

Finally, if you get a new HD for TM and you want to find a use for your 160Gb external, it would be ideal for use with SuperDuper! (once they've made it Leopard-friendly). That will give you a bootable clone (handy!), although you can't zoom back in time like you can in TM.

HTH - GL!
SL

 

[absurdio]

When you start Time Machine for the first time, it copies your entire hard drive. Then on subsequent backups, it only copies new and modified files. When the TM HD gets full, it deletes its own backups, starting with the oldest.

So you had about 30Gb free on your main HD, so you should've had 30Gb free on your TM HD after the first backup, space which would have been used to backup subsequent iterations of individual files. Sounds like a lot, but it also sounds like TM managed to eat this pretty quickly. Perhaps you've been editing / working with large files (or lots of small ones).

I also think TM counts a file as "modified" if it is changed in any way whatsoever. Ie, files that are only part-modified, date-changed or just moved will all be backed up the next time TM runs.

An example: Like you, my main HD is 160Gb with 20-30Gb Free, but my TM HD is less than twice the size, at 300Gb. I installed Leopard on 30th November, and TM can see all the way back to then - and I still have 129Gb free on the TM HD! (I'm not excluding anything either). In that time, I've mainly been doing a load of audio editing. I guess I'd have a lot less space left on my TM drive if I'd been (say) video editing.

Another tip: If Time Machine backs something up that is taking up loads of space and you're 100% sure you never want to see it again, you can delete it (and all iterations of it) permanently from the TM drive. Highlight the file in TM, click the cog button and check out the delete options you are offered.

Finally, if you get a new HD for TM and you want to find a use for your 160Gb external, it would be ideal for use with SuperDuper! (once they've made it Leopard-friendly). That will give you a bootable clone (handy!), although you can't zoom back in time like you can in TM.

HTH - GL!
SL

Thanks a ton. You've been both very patient and very helpful.
For the time being, my makeshift solution has been (as per your suggestions) to exclude some very cumbersome files/folders from my TM backups. And, actually, I was exactly wondering what I'd do with my 160Gb drive if I got a more appropriately sized drive for Time Machine; your foresight is remarkable. You'd think Time Machine would also make a bootable copy (is Time Machine of no use at all if your internal drive fails?), but perhaps we'll have to wait for OS 10.6: Ocelot for that...

 

[Applespider]

(is Time Machine of no use at all if your internal drive fails?)

It's not entirely useless so long as you have a new internal drive to install OS X on. While setting up Leopard, one of the options for migrating data is from a Time Machine backup rather than just from another Mac.

 

[superleccy]

Thanks a ton. You've been both very patient and very helpful.

YVW.

It's not entirely useless so long as you have a new internal drive to install OS X on. While setting up Leopard, one of the options for migrating data is from a Time Machine backup rather than just from another Mac.

I was about to say exactly he same thing!

But check out SuperDuper anyway. It's a lovely little bit of software and reasonably priced too. The scheduling works well, and the clones it produces are perfect. It's not Leopard-ready yet but they're working hard at it (and no, I'm not on comission).

I use TM and SD! for extra safety.

SL

PS: Just be careful when you're setting them up. The only time I've ever actually lost data is when I've stupidly told a backup program to back up to a drive I didn't intend - each time is was cheerio to the data that was there in the first place. Oh, the irony...

 

[gloss]

It's not entirely useless so long as you have a new internal drive to install OS X on. While setting up Leopard, one of the options for migrating data is from a Time Machine backup rather than just from another Mac.

Yeah, I'm actually prepping to use Time Machine to clone my system to a new HD I'm installing in my MacBook.

Very useful.

Anyway, people here are correct. The first backup is full-sized, any subsequent backups are incremental and much smaller. I'm not quite sure of the rate at which it'll eat hard drive space, but I suppose it depends on how much you're changing your files. If you work with video and graphics constantly, the incrementals will probably eat a lot more space, but if you're mainly a text/internet/IM/music guy like me, it shouldn't take much at all.

I guess Time Machine also does a bit of file management itself...it keeps 24 hourly backups, 30 daily backups, and then a bunch of weekly backups for any time further back than that.