After The Apple Repair: Fixing Time Machine
I recently had a whole trial at the Apple Store, that ended in the replacement of my MacBook Pro's Main Logic Board. Time Machine, while it's fucking amazing in terms of actually backing up your machine to disk, is set in its ways about some things. Specifically, it tags the backup folder on the external drive with your Ethernet MAC address. Which, when you swap out the logic board, will change.
So, here's how you FIX that problem:
First, you have to do some permissions voodoo. Open up Terminal, and navigate to your Time Machine drive's slash (root, base-level)
chmod -N Backups.backupdb
cd Backups.backupd
chmod -N yourbackupname
The Backups DB is ACL'd. We'll talk more about this here in a second, because this is a pretty...non-gentle way to fix it. chmod -N, new in Leopard (and Tiger Server...) removes the ACL control from these folders. This is a Kludge. However, it's what I had to do.
Once you have stricken the ACL's from the directories, it's time to change the attribute associated with the MAC address. xattr is the eXtended ATTRibutes library that allows you to do some pretty fancy dancing behind the scenes without having to do a whole lot of extra programming. It's a way of tying things together with a nice bow. Want to dink around with it more? xattr -h at the command line is the short guide. There's no man page for it.
So, here's how that works. You need to tell the Backup Director what your NEW MAC address is. Find it under Apple System Profiler. Then, tell the backup who you are:
sudo xattr -w com.apple.backupd.BackupMachineAddress 00:17:f2:xx:xx:xx backupname
Fill in the MAC address. Fill in the backup name. Then fire up Time Machine and it will recognize your drive again...
Or, at least, it's no longer failing here. I have a feeling Time Machine needs to reindex what's already on the drive and then do a big compare and then do a massive write. As I type this, though, it's at least added an InProgress entry for today's date into the same folder where all the others live... Happy thoughts.
About the ACL....no idea what happens now. Is Time Machine smart enough to restore that ACL after I've ripped it out? Good question. No freakin' clue. I'll update this section
Hat Tips: David Leber, Dave Schroeder, Jon Thompson, Barry John Williams
Comments:
Rather than the system profiler, since you're already at the command prompt, ifconfig -a will also spit out the MAC addresses of the various network devices.
Posted by Phearlez on January 14, 2008 — 11:47 AM
Brilliant. Thank you.
Worked like a charm.
Posted by mashby on June 10, 2009 — 7:11 PM
I'm running OSX 10.5.8 and it's worth noting that the Backups.backupdb file does not exist on the Time Capsule drive itself, it exists in the MOUNTED sparsebundle (aka the disk image).
eg:
No: cd /Volumes/TimeCapsule/ComputerName_MACaddress.sparsebundle
Yes: cd /Volumes/Backup of ComputerName/Backups.backupdb
If your logic board is changed, obviously Time Machine does not know to mount the old sparsebundle, so you need to double click on it (or use Disk Utility) to mount.
The comment here explains the complete process perfectly for a Time Capsule, while the original post refers only to an attached hard drive.
http://www.macosxhints.com/comment.php?mode=view&cid=101458
Posted by twitter.com/seekul on November 12, 2009 — 3:16 AM