Use Disk Utility to manage disks, add and manage volumes, and manage RAID disk sets.
Let macOS manage space between multiple volumes
Apple File System (APFS), the file system in macOS High Sierra, automatically allocates free space between volumes as needed, so you don’t need to manually manage volume sizes. To verify that your volumes were upgraded to APFS when you installed macOS High Sierra, select a volume in the Disk Utility sidebar—its format is displayed in the middle of the window.
Keep your external storage devices secure
When you get a new flash drive or external storage device, format it as APFS and encrypt it with a password to protect its contents. To get started, select your device in the sidebar, click , then click the Format pop-up menu and choose APFS (Encrypted).
Give your disk a checkup
If you’re having problems with a disk, Disk Utility can tell you if the disk is working as expected and repair problems it detects. To check, select a disk or volume in the sidebar, then click .