backuptime-machine
I have reinstalled my OS and copied my user account from a Time Machine backup using Migration Assistant. However, now when Time Machine starts a back up, it says that it is copying 200 GB, which is the total size of my hard drive. It seems that it has failed to identify my current user account as the same one that it already has back ups of.
I have tried changing my UID to match that of the Time Machine back up. My UID now matches, but it still insists on backing up from scratch.
This is the built in data transfer tool for Macs.
You can find it in /Applications/Utilities. You'll want to do the following:
Plug in your Time Machine backup drive, open Migration Assistant and select the From another Mac, PC, Time Machine backup, or other disk option:
Select the From a Time Machine backup or other disk option:
Select your Time Machine backup and click Next.
It should show you your old user account, which will have a drop down menu to select all the things you can restore.
Follow the prompts to restore.
This method will create a new user account alongside the one the Apple Store folks created for you. You'll be able to log out of the account they set up and log into your own.
Navigate to /var/db by pressing Shift + ⌘ + G and typing in the path.
Find the .AppleSetupDone file and delete it. It will likely ask you to authenticate as an administrator.
Restart your Mac.
Use the Setup Assistant to select a Time Machine backup to restore from.
This method does not delete the existing user account, but simply creates a new administrator account alongside it and allows you to use the Setup Assistant to restore from the backup.
You will need to delete the account the Apple Store folks set up for you if you don't want it anymore.
Good luck!
Four options are available for you - none of them is a clear winner that works in all cases:
tmutil inheritbackup commandThis last option has gotten me over the hump several times when clients cannot afford to lose their backup. I image their backup drive before starting (just in case) and then use the Time Machine System Preference options to exclude most of the drive. The first option is the most precise if you are comfortable with the terminal application and command line tools.
By excluding everything except perhaps /Library and /System you should be between 10 and 30 GB for the estimated size of a Full Backup and Time Machine will let you make a new backup. Then the trick is to slowly remove items from the exclusion list in stages to not have the next backup estimate exceed the remaining free space on your backup volume.
Best Answer
I saw your question before, but was at a loss to provide specific information. However, I took a look at Pondini's OSX and Time Machine Tips.
In particular on the page, How Local Backups are Stored, I noted that it's actually the hardware address, not the user ID, that is used as identification by Time Machine. From the page:
However, on the same page, Pondini goes on to say that each backup volume is assigned a Universally Unique IDentifier (UUID) that is in the extended attributes of the volume. Pondini says that this "should" cause Time Machine to automatically recognize the old backup.
However, if Time Machine does not automatically recognize the old backup via the UUID, then there is a procedure for manually restoring the association.
It's getting fairly involved at that point, and though it might be worth the effort from an investigative standpoint, you might be better off starting your Time Machine backups from scratch (just to wipe the slate clean, so to speak).