Guess what? RAID support is back in Disk Utility in macOS Sierra. You won’t find it in the main interface (see below), but you will find it in the File Menu. Dave Hamilton and John F. Braun discussed this on Mac Geek Gab 623.
RAID was long supported in Disk Utilities in OS X, but disappeared in OS X 10.11 El Capitan. It’s return is likely to be very welcome to power users.
Disk Utility in macOS Sierra
First, here’s the new main interface for Disk Utility in macOS Sierra. Note the lack of RAID options:
But wait, what’s this under the file menu? RAID Assistant? Why yes it is!
RAID Assistant in macOS Sierra
If you select that, the main interface in Disk Utility becomes RAID Assistant, as shown below:
Supported RAID modes include RAID 0 (Striped), RAID 1 (Mirrored), and Concatenated, or JBOD, or Just a Bunch of Drives.