RAID 0 Using Mac Disk Utility


Set up a RAID 0 striped set using Mac OS X Disk Utility

The purpose of this series of articles is to provide some documentation on the use of Mac OS X Disk Utility. The need for this documentation increases as new storage devices show up on the market requiring the use of Disk Utility to implement RAID. The new devices requiring Disk Utility include: the Promise Pegasus J4, the LaCie 5big Thunderbolt, and the USB 3.0 hub RAID, to name a few. This article will cover the creation of a striped RAID set using Mac OS X Disk Utility. A future article will cover the creation of RAID 10 a “striped set of mirrors”.  (In the interest of full disclosure: Following the links to Adorama.com provided above, and buying something, will support this site. Thanks!)

The reasons for creating a striped RAID set include maximizing the speed and capacity of two or more disks by combining them into a single volume.  In the chart below, two 1TB, 7200rpm, bus powered, USB 3.0 drives were striped together to create one disk volume that has twice the speed and twice the capacity of each disk separately:

Example RAID 0

The reason for not creating a striped RAID set is the increased chance of losing data. The loss of any drive in a striped set results in the complete loss of all data in the set. A four drive striped set is four times more likely to experience a drive failure than a single drive, assuming all drives are equal. A strong backup policy is required no matter how you store your data. A future article will discuss appropriate backup strategies.

Step by step instructions:

  • Attach all drives to be included in the striped set to the computer.
  • Start Mac OS X Disk Utility.  (To find Disk Utility, simply click the magnifying glass in the upper-right corner of the Mac screen and type in “Disk Utility”.)
  • Ensure all drives to be included in the striped set are visible in Disk Utility.
  • If any drives were previously part of another raid you may have to “Erase” the drives first.
  • Select any one of the drives to be included in the striped set and then choose the “RAID” button.
    • RAID Set Name: Choose any name you desire.
    • Format: Mac OS Extended (Journaled)
    • RAID Type: Striped RAID Set
  • Drag and Drop each of the drives to be included in the striped set from the list on the left to the window on the right.
  • RAID Set Size: Should be equal to the product of the total number of drives and the size of the smallest drive in the set:

RAID 0a setting up the disks

  • Press the “Create” button. A pop-up will appear that will ask you if you want to create a RAID set with the selected drives.
  • Press the “Create” button in the pop-up:

RAID 0b Ready to build

  • When complete, Disk Utility will mount the new drive and the new drive will be visible on your desk top just like any other drive:

RAID 0c Stripe Set Complete

  • Selecting the newly created Striped set from the left hand list of drives, then selecting “First Aid”, then clicking on “Verify Disk” should result in the following display:

RAID 0d Stripe Set Verified

 

Complete!

 

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