Repair Time Machine after Computer Upgrade or Logic Board Fix
Some weeks ago, I got a new MacBookPro and installed the new system using my Time Machine backup disk - great feature! After installation, it was the very same system, I was working at before - except for some minor changes (like the MAC address, etc). Anyhow, Time Machine did not want to re-use the old Time Machine backups on my new laptop and hence started a new directory. I left the old directory on my disk, even without being usable at all and today, I found a page, which is coping with a very similar problem and adapted it to my situation.
The basic steps are summarized in the following.
The Time Machine backup disk is assumed to be called Backup.
The hostname is MyMac
.
The old MAC address is 00:f9:e8:d7:c6:b5
and the new MAC address 00:1a:2b:3c:4f:56
.
Start the Terminal Application
Get the current MAC address using
ifconfig en0 | grep ether
Get the old MAC address by using
cd /Volumes/Backup/Backups.backupdb
xattr -p com.apple.backupd.BackupMachineAddress MyMac
Disable Time Machine in System Preferences
Disable ACL (access control list) using
sudo fsaclctl -p /Volumes/Backup -d
Move the old MAC address file to the new MAC address by
sudo mv .00f9e8d7c6b56 .001a2b3c4f56
Don’t forget to change the MAC addresses to yours.Write new MAC address to backup directory using
sudo xattr -w com.apple.backupd.BackupMachineAddress 00:1a:2b:3c:4f:56 Backups.backupdb/MyMac
Again, don’t forget to change the MAC addresse to yours.Move newly created backups into old directory, by
sudo mv MyMac\ 2/* MyMac/
The last command will result in a (harmless) error, which can be ignored. You can now delete the old directory ‘MyMac 2’ in the Finder.Re-enable ACL, using
sudo fsaclctl -p /Volumes/Backup -e
Eject and unplug the Backup disk
Re-Plug the Backup disk
Re-Start Time Machine (and possibly re-enable the Time Machine disk in Time Machine Preferences)
Unfortunately I have to note, that Time Machine will do a full backup after restarting. I tried to follow the comments on above site, but they all seem to be unrelated or even misleading - sorry.
Cheers,
iss