Has TM deleted everything?

Question

I believe I may have hit that one Time Machine scenario where as a user I've done everything properly to ensure my data is backed up, but Time Machine has (maybe) left me with no copies.  I'm part way thru my investigation and I'm desperately seeking some "no, there's no way it would do that" opinions to calm my panicking mind
Here's the story so far.
I have a late 2009 iMac running Lion with a 1TB drive in it, backing up to a Time Machine external drive.  About 2 months ago, I got hold of a 256GB SSD and replaced the optical drive with it, and now the SSD is my bootable OSX volume.  The "old" hard drive is still in the machine and contains amongst other things my very valuable and large Aperture library (~400GB) and iTunes library (~100GB).  When I first started using the SSD as the boot drive, Time Machine got a little bit confused and started telling me it couldn't back up, which was fair enough because the volumes had changed around a bit.  Anyway I thought it was a good enough time to temporarily retire the old Time Machine backup and as I had another spare 1.5TB drive laying around I brought that in and told Time Machine to use it.  I made sure to specify that I wanted not only the new SSD but also the old 1TB drive which contained those photo & music libraries.
Then, a couple of weeks ago, Apple sent me a product recall notice saying some of those 1TB drives have been failing and they'd replace it for free.  I rang the shop where I bought it and they said that the fact that I'd put the new SSD drive in (and voided Applecare) didn't matter and they'd still be happy to replace the drive because this was a product recall which is outside of Applecare.  (I thought that was mighty nice of them and an example of why I've bought 3 Macs there - Macworx Joondalup Western Australia, great guys).  Anyway I was about to take it in and then last night the 1TB drive died completely.  It no longer even shows up in Finder or Disc Utility.
As I was discovering this, I noticed the Time Machine icon spinning up the top of the screen and clicked it and it said "Deleting old backups".  Aaaaagh!  I stopped it immediately but I don't know what it had already deleted.  I've found on google that the default behaviour of Time Machine is that if the state of your Volumes changes, i.e. a drive is added or removed, that Time Machine will delete all old backups and start again with a fresh drive.  Which means now that my hard drive has died, then it is wanting to delete the backups of that hard drive.  Please tell me this is not so.
I navigated in Finder to the Time Machine drive and found that the last 2 backups don't contain my Aperture library, and there is one single backup before that which does have an Aperture library… I don't know how big this file (folder/package) is because I had to rush off to work where I am now, so I can't verify whether it's still intact.  Either way I probably don't want to touch that drive until I have the new one in the Mac.  But oh boy am I panicking.  I have the backup on the old retired backup drive, but that's 2 months old and since then we've added a heap of photos, including since the birth of our daughter 3 weeks ago.
Can anyone enlighten me on what Time Machine is likely to do when a backed up non-system drive like my 1TB one dies?  Please tell me that the default is not that it will immediately delete backups of it.
After this, I'm definitely investing in Crashplan or similar.

Answer 1

mcintosh_i wrote:
I've found on google that the default behaviour of Time Machine is that if the state of your Volumes changes, i.e. a drive is added or removed, that Time Machine will delete all old backups and start again with a fresh drive.
Not so (as long as there's room on your TM drive).
Each drive is backed-up separately.  Once a drive is no longer connected, of course it won't be backed-up anymore, but the old backups aren't deleted automatically or immediately.
However, when the TM drive does get full, and TM has to start deleting old backups, sooner or later, it will delete the last remaining backup of the missing drive.
If you replace a drive, it will probably be treated as a new one (depending on the circumstances), and be backed-up in full on the next backup, requiring a lot of space, and, if necessary, a lot of old backups to be deleted. Thus you might lose the old backups fairly quickly.
In some circumstances, if you replace your OSX drive, Time Machine will automatically "assocate" the new drive with the old backups, so only the changes will be backed-up.  As far as I can tell, that doesn't happen automatically with a data-only drive.
Effective with Lion, however, you can manually tell Time Machine to "associate" the new data-only drive with the old backups, via the procedure in #B6 of Time Machine - Troubleshooting.  That's a bit tedious, unfortunately, but if you're careful, it does work.  
Can anyone enlighten me on what Time Machine is likely to do when a backed up non-system drive like my 1TB one dies?  Please tell me that the default is not that it will immediately delete backups of it.
Correct.  It will not immediately delete the backups. 
You may not see them easily via the Time Machine browser, however, as you normally start from a folder on an existing drive, then Enter Time Machine to display the backups of that folder.  Since the drive in question is not present, you can't start from it.  Unfortunately, Apple doesn't make it clear how to do that, but the procedure in #E3 of Time Machine - Troubleshooting should work.