Join Nick Brazzi for an in-depth discussion in this video Understanding the new Apple File System, part of macOS High Sierra New Features.
- [Narrator] In Mac OS High Sierra, Apple is introducing a new file system. Now the file system does not change how you work with the computer. It's the system that controls how the computer stores and retrieves data from a hard drive. But as a user, the main benefit is that your computer will be able to read and write files much quicker if you drive is set up with this new file system. So let's look at something. I can see my computer's main system hard drive is visible here on the desktop. I'm going to right click on that and choose get info.
And here in this information panel I can see the format of this drive. This is APFS, this is that new file system. Now I also have an external hard drive connected to my computer. I can also see an icon for that on the desktop. So let's right click on that and choose get info, and we can see the format of this drive is Mac OS extended journaled. That's the older file system. This was basically the default on Mac computers before High Sierra. And on Windows computers there are other file systems that are used.
So here's the benefit for you. Assuming these two drives are basically the same type of hardware, the computer is going to be able to write files and access files from the APFS drive much faster. So working with files on an APFS formatted drive can make your computer feel much faster depending on what you're doing. And also some encryption systems will work better. Now don't worry, you can still continue to work with drives that are formatted with the older Mac OS format, they're just going to be a little bit slower.
So by default on a new Macintosh running High Sierra, the main system drive will be APFS. And if you upgrade to High Sierra from an older version of Mac OS it will automatically convert your system to APFS by default. That's why my system drive is already set up, I didn't have to do anything. But let's talk about additional drives that you might connect to your computer. If you use an external hard drive on your Mac, it's probably not formatted for APFS. But you can reformat a hard drive to use APFS using a program called Disk Utility.
So you could go into your applications folder or into Launch Pad. Here in Launch Pad I'll go to this other folder where I can find Disk Utility, I'll click on that and launch it. When you launch Disk Utility you will see every drive connected to your computer as listed over here on the sidebar on the left. This is the main system drive, this is that external hard drive that I have connected. So we can use this to reformat this external drive. But before we do this there are a few very important things you need to remember.
First, reformatting a hard drive will completely erase that drive. And this is fine when you buy a brand new drive, but if there is already data stored on that drive, you cannot reformat the drive without completely erasing all of that data. So be careful. And the second thing is that APFS drives will not work on all computers. Only Macs with High Sierra or the previous version of Mac OS which was called Sierra, only those two types of computers will work with APFS drives.
You cannot work with it on an older Mac running Mac OS El Capitan or earlier, and you certainly cannot work with it on a Windows computer. But with that in mind, if you're sure that it's the right thing to do for your situation, here's how you can reformat your drive. Just select it here in Disk Utility, then hit this button up at the top that says erase. Make sure you do have the right drive selected because we are going to erase the drive. At this point you've got the opportunity to change the name of the drive if you want, I'm not going to bother with that, I'm just going to go to this menu and I'll choose this first option for APFS.
Now you may find that some drives cannot be formatted as APFS. Fusion drives cannot be converted to APFS and it will not work on small capacity USB memory stick either. But if it is supported for your hard drive you'll have it here on this menu, all you need to do is select it, hit erase, and it takes some time depending on how big the drive is, but just give it a little bit of time to finish. And when it's all done you'll get this message here so you can just click done and you can quit Disk Utility.
Now when you reformat a hard drive it may ask you if you want to use that drive as a time machine backup, just go ahead and answer that question, you can hit the button that says decide later, or you can hit don't use if you want. But now this drive is completely reformatted. I can right click on it, I can go to get info, and I can see the format is now APFS. And any data that may have been on that drive is now gone. So now I have a nice, clean APFS formatted drive and I can start working with it and it will generally run faster than it would have before.
So now you know a little bit about the new APFS file system and you can get your secondary drives formatted if you want.