Choosing a RAID format in macOS Sierra’s Disk Utility.
Choose your type, then click Next.
The next step is to select your storage devices. Disk Utility will show the drives eligible for the RAID format you select. The app shows the disk, and underneath each disk is a list of the partitions on that device. (When you take the space of a storage device and divide it during formatting, you are creating partitions.)
Click on the checkbox next to the disks you want to include in the RAID. When you select a disk, all the partitions are automatically selected.
Select the disks you want to include.
When setting up a RAID 1, you have to decide if a drive should be a RAID Slice or a Spare. A RAID Slice means the drive is an active part of the array and mirrors your data. A Spare is a drive that sits in waiting until a Slice fails, then data is mirrored to the spare automatically. If you have two drives, they each need to be set as RAID Slice. If you have more than two, you can set one as Spare.
Click the Next button after you’ve selected your disks.
Now you need to set the properties for your RAID.
Name: Give your RAID a name, like you would your hard drive.
- Format: Most people should select Mac OS Extended (Journaled). Select Mac OS Extended (Case-Sensitive, Journaled) if you want files with the same name but with different case treatments (Science Report.txt and science report.txt, for example) to be saved as separate files.
- Type: This is what you selected back at the beginning of the procedure. To change it you have to start over.
- Capacity: This is based on the drives you selected in the previous step.
- Chunk size: Since data is written across drives, it is broken into pieces. Chuck size determines the size of those pieces. If you work with large files, like with video or 3D graphics, choose 128K or 256K. If you are a more general purpose user who does email, writes, or works in spreadsheets or databases, choose 32K or 64K.
- If you are building a RAID 1, you’ll see an option to “Automatically rebuild.” This means that if a drive is removed and then replaced, the data will automatically be restored to the new drive. Check this box if you want this option. If you don’t, you rebuild the RAID using the Disk Utility app.
Once you click Next, your Mac will start to configure your RAID array, so don’t click it until you are ready.
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