14
Creating a RAID Volume
(Macintosh OS X version 10.6.x or Later)
Mac OS X 10.6.x or later Disk Utility RAID (Redundant Array of Independent Drives) options
allow the user to display multiple disks as a single volume. A RAID 1 mirror can provide data
redundancy in the case of a hard disk hardware failure. A RAID 0 striped RAID set, can
increase performance and volume size by striping multiple disks into a single. Both methods
are described below.
Mirrored RAID Set
- Apple Disk Utility can be used to create a mirror. This is also known as
a RAID 1 configuration. The hard disks should be the same size and model for optimal
performance. Data written to a mirror volume is archived onto two separate duplicate hard
disks. The mirror configuration provides redundancy that will usually protect data should a
single hard disk fail. A mirror cannot protect against the user accidentally trashing an
important file. In addition, if the mirror hard disk directory becomes corrupted, the corruption
will be copied to all hard disks in the mirror configuration. As a result, a backup copy should
always be maintained of any important data on the mirror. RAID 1 mirror performance equals
the performance of the slowest hard disk in the mirror set. The RAID 1 mirror volume size
equals the size of the smallest member disk. All data on hard disks used to create a new
Disk Utility based mirror will be destroyed when the mirror is created.
Striped RAID Set
- Apple Disk Utility can also be used to create a stripped RAID set. This is
also known as a RAID 0 configuration. The hard disks should be the same size and model
for optimal performance. Data is spread (striped) equally across multiple hard disks for
increased performance. A stripped RAID set provides no data redundancy. As a result,
should one hard disk fail all data stored on the RAID 0 volume is lost. While a stripped RAID
set provides excellent performance, a back up is required to protect important data. RAID 0
direct connect performance usually equals the performance of the slowest hard disk in the
RAID 0 x the number of hard disks used. The RAID 0 volume size equals the size of the
smallest member disk x the number of disks in the RAID 0. All data on all hard disks used to
create a striped RAID set will be destroyed when the RAID 0 is created with Disk Utility.
Step by step instructions
1. Turn on your computer.
2. Open Apple
Disk Utility,
which is located in the Utilities folder of the Mac OS X start-up
volume.
To open Disk Utility please do the following:
a) From the Finder, click on the Go menu
b) Pull down to Utilities and release the mouse button
c) Double click the Disk Utility Application
3. Review the list of hard disks show within
Disk Utility
. Hard disks that have been formatted
should have a volume name below their listing. New, unformatted disks typically have no
volume name. Carefully select the hard disk you wish to format.
4. Select the
RAID
tab in Apple’s
Disk Utility
(see Figure 8)
