Finally, Apple has updated from the ancient HFS+ file system to the new APFS. Faster, more efficient. Nice. But how can I convert an external drive to APFS?
File systems are one of the technologies we don’t think much about on a daily basis, but make our computers, phones, tablets, even DVRs work smoothly and efficiently. You might never have given it a moment’s thought, actually, but there’s a long history of file system development. At its most basic, the file system organizes the vast sprawl of data space into blocks and hooks them together so you can have big and small files, folders, and an entire file system hierarchy.
Disks keep getting bigger, however, and a file system that worked for a 20MB drive back in the day was already a bit clumsy for a 2GB drive. Jump up to 2TB or more and it becomes obvious that the size of files and the number of files on the drive is going to be much, much bigger too. Enter the newest solution: Apple File System, APFS.
Upgraded to MacOS X 10.13 High Sierra or its more recent cousin Mojave? Your boot drive automatically switched formats from HFS+ to APFS! Running iOS 10.3 or higher – the latest as of this writing is iOS 12! – on your iPad or iPhone? You switched over to APFS too. Congrats, you probably didn’t even notice other than perhaps seeing that it did file operations like moving or duplicating even massive files was accomplished much more quickly. So odds are good you’re already running APFS. Nice.
However, if you have external disk drives, those are probably not running APFS and are still HFS+ formatted drives. Here’s how you fix that…
You want to plug in the drive and launch “Disk Utility“. You can easily do that with Spotlight but it’s also found in the “Utilities” folder within the “Applications” area. Choose your external drive – mine is a LaCie 2TB drive – and here’s what you’ll see:
See on the top where it says “Mac OS Extended (Journaled)”? Yeah, that’s the old format. My boot drive shows this:
Before you upgrade, let’s just run a quick disk repair to ensure it’s all formatted correctly and is ready to go. That’s done by choosing the drive, then clicking on the “First Aid” button on the top toolbar. The program will verify what you’ve requested:
You do, so click on the “Run” button. A progress window pops up and you can click on the “Details” link to open up the lower window and see what’s going on. Kinda like this:
Ah, looks like my disk is in good shape. Excellent.
To proceed, again ensure you have the correct disk selected, then from the Edit menu choose “Convert to APFS“:
It’ll inform you that this means your disk won’t be backwards compatible with older versions of MacOS X:
Remember, if you have multiple Mac systems, this just means they’ll all need to be running High Sierra (10.13) or newer to be able to work with the drive. You’ll gain speed and greater reliability against data corruption if you do opt to upgrade.
Ready? Click on “Convert“…
This time the detail is a bit more, well, detailed. Notice that Disk Utility is actually just invoking a command line sequence, the MacOS X command line utility “apfs_hfs_convert”. It chugs along fairly quickly; my 2TB drive took under 90 seconds to complete.
That’s it. Done. Now you can see in Disk Utility that the external drive shows up a bit differently:
Can you see what’s different other than it saying APFS? There’s a “Container” level in the disk partition and format hierarchy on the left. Nothing you need to care about, actually, but interesting to note. That’s it. Done. Welcome to Apple File System APFS.