How does Time Machine work?

Well, and your point being?

You don't want to use Time Machine for backups, good for you. There will be people who have been praying for a feature in OS X like this. Maybe without all the eye-candy.

When reading your post and putting it through the Raymond Chen filter, it comes back as, "I don't do anything interesting, and if I deleted everything, it wouldn't matter"

 

I think Sanford's got a point though - has anybody stopped to consider exactly how much storage Time Machine is going to require over time?

So you take some photos on holiday, come back and put them into iPhoto (which stores the originals as well as any changes), and they get backed up. Any changes you make (I suppose) will also get backed up.

Now your music - what if you have a 10Gb music partition - maybe you edit some of the meta info associated with an mp3. That all gets backed up.

Now extrapolate that over a year or two, and how much storage are we all actually going to need?

 

I'm pulling up a chair and getting ready for this little fight...

Back to your corners, on the sound of the bell come out fighting, no punching below the belt.


DING DING - Round 1

 

There was a YouTube clip of Scott Forstall explaining this at WWDC, which i shall now try to find.

Here we are. Does this help? http://www.youtube.com/watch?v=X2OPprfi3Dk

 

Time Machine deletes the oldest copies of files as and when more space is required for new files.

 

Thanks - that's all well and good (and it is good that it does that), but size the external disk too small and it'll just end up overwriting backups you may need to return to at a future point, if that makes sense..

 

TM backs up once fully, then only the changed files after that. So if you have a 120GB main HD (completely full) and a 160GB backup you will then have all 120GB backed up and 40GB left over for changes. That is, if you change <40GB of data, your backup drive will not fill up. I will assume you are not running your 120GB drive at full capacity though so that leaves considerably more room for backups. You can also tell TM to limit the amount of space it uses and which folders to back up so it will only keep as much backup as you have allowed.

 

Makes sense... I assume it only backs up user data and not the OS / Applications?

 

A solution to the problem I read a few posts up is to do those temporary things with time machine OFF. That way when you intentionally delete your movies/music it won't be holding that back-up when you do. Turn it back on accordingly.

Of course. But that's like getting angry that the iPod shuffle you bought won't hold all your music. I think I see a way out of this.

 

I believe it does everything by default. Including apps, Library, etc. The point being you can fully restore a machine from a TM backup.

 

Yep, but you can add/remove locations that you *don't* want TM to backup, much like you can add/remove the locations Spotlight searches through.

 

This is the best explanation I have seen to date:
http://www.appleinsider.com/articles/07/10/12/road_to_mac_os_x_leopard_time_machine.html&page=2

 

All positive stuff

However, thinking of non-technical home users out there (some of whom I have the pleasure of supporting ), it sounds like it could be quite complex to set up to get the best use out of the storage available

I can already see the conversations in the future:

"you ran out of space so TM overwrote the backup that we now need"

"but you told me a 250Gb would be more than sufficient"

"I know, I'm sorry, but actually you need to buy a bigger disk now"

 

Is there no way to prioritize items in there? Say command it to never delete iPhoto libraries and things like this. (?)

I imagine it warns you before deleting things, right?

(honestly asking, I'm not sure)

 

All looks good.

Can I tell Time Machine, for example, not to backup my iTunes Library?

 

Yes

 

Sweet, thanks.

 

But Time Machine does not hold the information forever. The DVD rips will get backed up the first time they are seen. Then over the course of the next few months, if you do a lot of DVD ripping, TM will run into either the back up drive hard limit or the artificial limit that you set. TM will then start to delete the oldest files that are no longer on your computer. If you haven't deleted anything other than the DVD rips TM will eliminate those.

Another idea would be to create a folder for the DVD rips or whatever other temporary files you have and tell TM not to back up that folder.

The TM backup isn't going to stop working because you run out of space, it will simply limit the amount of time you can trace back in the past. If you currently do your own, daily, weekly, monthly backup then you probably just take a snapshot of your HD at that time, giving you no recourse to go back any further than that point in time. If you're only doing weekly or monthly backups you also run the potential for losing up to a week's or month's worth of data if you have a hardware failure, where if you manage to remember to plug in an external drive every night or so you can limit your losses to only a day, less if it's a static machine always connected to an external drive.

I don't currently have an external HFS drive but TM is making it very tempting. Maybe I'll buy a couple of 120s or 160s and update my PowerBook HD and create an external as well. I have, in the past been pretty good about backing up my laptop on a weekly basis to my PC at home (mirrored RAID), with a monthly backup of that PC to an external drive. I do however miss weeks and months sometimes so TM would be an extra, or more consistent backup solution as a first level.

 

I am worried it won't work

I have my iTunes library and iPhoto library on a 500 GB external drive. I know TM will backup my Macbook Pro's 160 GB drive to an external drive. But I don't know how I'll backup my external data drive to another external drive. I want to keep my Macbook Pro's backup separate from my external data drive backup.

The main reason to separate them is because I actually have 6 external drives with data with 6 external drives to manually backup those drives.

I might need Time Machine Pro if such a product could exist.