If you don't know, when you upgrade your mac, your Time Machine existing backups will not work with the new system. Apple's intention is to apparently force you to format your external disk, or manually delete your existing backups, and start Time Machine (“TM” from here on) anew.

Steps are published all over for how to do this, but they all seem to be missing one component from what I've found with Snow Leopard- namely that the xattr attribute must be entered in ASCII Hex for things to work properly.

Also, Snow Leopard does not include the binary fsaclctl, which is necessary to update the settings on the Time Machine disk. You can either try to find a copy of fsaclctl online, or find out what command has replaced it. If you obtain a copy of the fsaclctl binary, copy it to your /usr/sbin folder.

Steps to get your existing backups working again are essentially:

1. Backup your current settings so you can back out the changes if you need to
2. Get your new hardware Ethernet MAC address
3. Allow edits to file system attributes on the TM disk
4. Edit the attributes and files
5. Disable edits to file system attributes on the TM disk
6. Re-plug your TM disk & test backups

Steps in detail:

• Attach your TM disk
• Open Terminal
• Type:

  cd /Volumes/TM

  where “TM” is the name of your TM disk

• Copy the .MACaddress file to the same name with .bak. Ex:
• Type:

  cp .0016cb9268a5 .0016cb9268a5.bak

• Backup the attributes on the backupsdb directory. Ex:
• Type:

  xattr -l Backups.backupdb/systemname >> ~/systemnamehex.txt

  Where systemname is the name of your system disk.

• Open Terminal (probably already opened)
• Type:

  ifconfig en0|grep ether

• Copy or make a note of the string after the word “ether”. That is your MAC address.

• Open Terminal (probably already opened)
• Type:

  sudo fsaclctl -p /Volumes/TM -d

• Open Terminal…
• Type:

  cd /Volumes/TM

• We need to
  unix/osx/change_time_machine.txt · Last modified: 2010/02/22 05:45 by ben