I recommend using Coriolis Systems's $50 iPartition for this step if you've got some cash to spare (or already have the utility). After launching iPartition and choosing the new drive from the app's list of drives, you'll see a pie chart of the drive's partitions, including all unused space in gray. You simply drag the edge of the Media "piece" of the pie so that it encompasses all that gray area and then click the Commit button in the toolbar. In a matter of seconds, your Media partition is its rightful size. And because there was no data on that free space, you don't even have to worry about losing data—generally one of the risks of repartitioning a drive. (If you've already got a copy of Prosoft's Drive Genius or Micromat's DiskStudio sitting around, these utilities also let you repartition a drive without reformatting it.)
If you don't already have a partitioning utility, and you don't feel like springing for one, the process is still doable, but a bit more complicated (and perhaps a bit intimidating if you're not comfortable with Terminal). Here are the steps; if at any time you see the Finder's "unrecognized volume" error, click on Ignore:
1. In Terminal, type
diskutil list yet again to be sure you’re working with the correct drive and partition; once you’ve found the drive, look for the partition on that drive that says “Apple_HFS Media.” Note the device number (on my drive, disk4) and the partition number (the number farthest to the left, 4 on my drive).
diskutil eject disk# (where # is, again, the device number). This ejects the new Apple TV drive so you can work with its partitions.
gpt remove -i ## disk#, where ## is the partition number and # is, again, the device number. For example for my disk, the command would be
gpt remove -i 4 disk4. This command deletes the current Media partition. (If you’re curious,
gpt is the GUID partition table utility.)
diskutil eject disk# again. (You need to eject the disk before using the gpt command each time. A hassle, but necessary.)
gpt show disk#, where # is, again, the device number of the drive. This command shows you the current partition layout of the drive; here’s the output for my drive:
start size index contents 0 1 PMBR 1 1 Pri GPT header 2 32 Pri GPT table 34 6 40 69632 1 GPT part - C12A7328… 69672 819200 2 GPT part - 5265636F… 888872 1843200 3 GPT part - 48465300… 2732072 312581775 312581775 32 Sec GPT table 312581807 1 Sec GPT header
You’ll notice one very large empty area; that’s the space that’s currently unused. On my drive, it starts at block number 2732072 and is 312581775 blocks in size. (In the output above, I’ve shortened the contents column for index 1, 2, and 3 to fit this page; you’ll see much longer strings of characters there.)
diskutil eject disk# to eject the disk again.
gpt add -b _START_ -i 4 -s _SIZE_ -t hfs /dev/disk#, where START is the starting block of the free space (2732072 for my disk, above) and SIZE is the size of that space (312581775 for me). This command tells
gpt to create a new partition, partition #4, starting at block number START and ending after SIZE blocks.
diskutil eraseVolume "Journaled HFS+" Media /dev/disk#s4 (# is the device number, 4 is the new partition number). This command formats the new, larger Media partition so that it’s ready for use.
Whew! Your Media partition should reappear in the Finder; Get Info on it to see its new, more spacious size. In my case, nearly 148GB. (The free space is less because I performed my upgrade after having synced data from iTunes to the original drive, and I used iPartition to resize the Media partition; so my original data was preserved. If you used the Terminal method to repartition, your Media volume will be empty.)
Putting it back together
Now it's time to put your Apple TV back together again, a fairly painless process. First, connect the ATA cable to the new drive. Then place the two adhesive pads on the drive in the same locations from which you removed them from the original drive: the large double-stick pad goes on the bottom (the side with the four mounting-screw holes), the small pad goes in the lower-right corner.
Gently press the drive against the Apple TV's bottom plate so that the drive's four mounting-screw holes line up with the four holes on the bottom plate; then replace the four Torx-8 screws and tighten them. Finally, replace the bottom plate and fasten it in place with the four Torx-10 screws.
Connect the Apple TV's power and connection cables (the latter I'm assuming are already hooked up to your TV), and the Apple TV should start up normally. If it doesn't, don't worry—there's one more step you should take, regardless of whether or not the new drive works right away. I recommend using the Apple TV's Restore feature to reset your Apple TV back to its original configuration. If you'd previously been using your Apple TV, this means you'll have to go through the setup process again, including re-syncing your media, but the Restore process ensures that your new drive is in like-new working order.
To perform a restore, hold down the Menu and Down (-) buttons simultaneously for approximately six seconds; you'll eventually see the Apple TV's status light blink off and then on again. This will bring up the language-selection screen, and then the Apple TV Recovery screen, which gives you options to Restart, Run Diagnostics, or perform a Factory Restore.
Select Factory Restore and press the Play button; confirm your selection on the next ("Are you sure?") screen and the restore process will begin. It should take only a few minutes; you'll see a progress dialog on the screen during the process. Once the restore is complete, the Apple TV will restart, the initial startup movie will play, and the setup process will begin.
Once you've completed setup, go to the Apple TV's Settings menu, and then choose About; assuming all went well, the Capacity should now reflect the larger size of your new drive!
You should also see this new, larger size in the Summary screen of iTunes' Apple TV display. For example, here's mine just after syncing started: