The Mac should be recognised as a different machine.. and there are some important clues to doing this.
I also strongly recommend you read and try to understand what TM does.. it is not super easy.
The section of restore in FAQ above gives you a lot of info.
Also can I suggest making a disk image with another software.. superduper does this very well and is free for the disk image.. last time I looked anyway.
You should recover and then do a new TM backup and start over.
Thanks - although that sounds more complicated than I thought it needed to be.
The scenario is:
One iMac with one backup going to one TC.
The hard drive in the iMac is being replaced.
So I thought it was just a case of being either:
1. Restore system from Time Machine option when booting into recovery.
2. Using Migration Assistant if Time Machine deems the iMac to be 'new' because its not the original hard drive.
This may have answered that question;
Restore From Time Machine Backup: You have a backup of your system that you want to restore. If the problems your Mac is having are serious enough that you need to erase your startup drive (perhaps using Disk Utility in recovery mode, below), or if you’ve installed a new hard drive in your Mac, this option lets you restore, from a Time Machine backup, your entire system, including the OS and all accounts, user data, and settings.
Something TM cannot do? So Restore From Time Machine Backup will likely have problems? (or at least with a TM backup) Not so good.
So how does SD work exactly? Does it create a second backup on the TC, so when I get to Restore From Time Machine Backup, I'd select the backup created by SD, rather than the one created by TM? Or is there more to it than that?
TM cannot restore a fully working computer EXACTLY.. as the original in the time. It is not designed to do that.. it is designed to be smart.. too smart is a problem.
Plug a USB drive into the computer.. use superduper to create an exact bootable image on the usb drive.
Change the boot from the internal to the external drive..
When the computer comes back from Apple.. plug in the external drive.. set it to the boot drive.. use superduper to again copy the whole thing back to the internal drive.
But you can do it via the image you store on the TC disk.. You restore it via a boot disk with superduper. This can be a usb stick so it doesn't have to be large.
Do a quick read.
An alternative.. is using a boot cd .. clonezilla.. that is also great.. although it is very Linux.. the menus are pretty simple to navigate.
None of this stops you from using TM..
If you want to do it via TM.. great.. strongly advise a fresh clean TM backup though.. TM by its nature of incremental backups over time is many times larger than the existing drive data. It takes ages to sort through.
And it can mess up permissions and all kinds of issues.. if you just have a read through the discussions here. It is not easy.
For a direct.. restore.. seeing your computer boot from an external drive exactly as it does from the internal drive is very comforting.
Thanks for all the replies - much appreciated.
I did just have an epiphany this morning though - if the Apple repair place has the machine in to replace the drive, they'll have access to the existing drive, so presumably they would be able to copy everything across to the replacement drive while they were putting the new one in?
LOL!! Sometimes we forget the obvious..
You might find them willing.. depends on technician on the day and policy of the place.. they might charge you a few dollars to do it..
But let me tell you from a Technician's viewpoint.. responsibility for backups is yours.. if they lose the entire drive.. that is really of little concern to them.. You are expected to be responsible for your own stuff.
The place is quite friendly - they replaced my LCD panel just a few months ago - it had a terrible case of the grey streaks, so much so that Apple agreed to pick up the tab even though the machine was a year out of warranty.
And I certainly wouldn't hold them responsible - I have a back up here on my TC after all. So if they were willing, even for a notional fee, I'd be happy to let them have first crack at it.