I found the initial Time Machine backup to a disk hooked up to my AirPort Extreme to be painfully slow. This procedure sped the process up enormously. The only tricky part about this is that you don't have to tell Time Machine you're moving the drive. I'm using an external disk with one partition formatted with "Mac OS Extended (Journaled)," and sharing it with a disk password.

First hook your USB drive up to your AirPort Extreme and configure the disks for Time Machine. Add the disk to your time machine and start the initial backup. Once Time Machine is past the "preparing" stage and is actually copying data, cancel the backup. This step creates the sparsebundle image that will contain the backup on the drive.

Unmount the disk. You'll probably also want to disconnect all users using the AirPort Utility. Disconnect the drive from the Airport Extreme and connect it direc...

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