About Disk Utility on Mac
You can use Disk Utility on your Mac to manage internal disks and external storage devices. Using Disk Utility, you can:
Format and manage volumes on physical storage devices.
Create a disk image, a single file you can use to move files from one computer to another or to back up and archive your work.
Combine multiple hard disks into a RAID set that acts as a single disk. Using multiple hard disks in a RAID set can increase the performance, reliability and storage capacity of your data storage system, depending on the type of set you choose.
Check for and repair errors on your disks and volumes.