macOS High Sierra introduces APFS (Apple File System) to Mac computers. APFS replaces Mac OS Extended (HFS+) as the default file system for solid-state drives (SSDs) and other all-flash storage devices.
Which format is in use?
To find out which format (file system) your storage device is using:
- Select the device in the Finder.
- Choose File > Get Info, or press Command (⌘)-I.
- Check the Format shown in the Get Info window.
Or use the System Information app: Select Storage in the sidebar, then check the File System column for your volume.
Which format should you choose?
When you install macOS High Sierra on the Mac volume of a solid-state drive (SSD) or other all-flash storage device, that volume is automatically converted to APFS. Fusion Drives, traditional hard disk drives (HDDs), and non-Mac volumes aren't converted.
Disk Utility in macOS High Sierra can format most storage devices using either file system. If you need to manually reformat, consider these points:
- APFS requires macOS High Sierra. Earlier versions of the Mac operating system don't mount APFS-formatted volumes.
- APFS is optimized for solid-state drives (SSDs) and other all-flash storage devices.
- Disk Utility tries to detect the type of storage you're formatting, then shows the appropriate format in the Format menu. If it can't detect the type of storage, it defaults to Mac OS Extended, which works with all versions of macOS.