Time Machine metadata


(This post is for our more advanced readers who are curious about how Time Machine stores its data.)

OS X stores Time Machine metadata in file extended attributes. These attributes can be viewed using the xattr command. To view this data:

1. Navigate to your Time Machine backup disk using Terminal.

2. cd into the Backups.backupdb directory.

3. You should see the name of your backed up Mac in this directory. Type:
xattr -l <name of Mac>

You’ll see some attributes listed. The BackupMachineAddress is the MAC address of the machine that was backed up. The ModelID is the model identifier (e.g. MacBookPro8,1) of the Mac.

4. cd one level down into the backup. You’ll see a list of backup timestamps. The metadata on each file includes the snapshot number, date, and the total number of bytes copied.

5. In the next directory level down, you’ll see a list of volumes, each with associated metadata, such as the timestamps of the oldest and newest snapshots.

6. Finally, each file in the backup will also include the timestamps of the oldest and newest snapshots.

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