Apple Xserve RAID: Using RAID 1.2 Admin and Disk Utility - Manual (Page 21)

Chapter 2 Working With RAID Arrays 21
5 Choose a format for the array from the Volume Format pop-up menu.
Note: You can take advantage of disk journaling by using the journaled volume format
in Mac OS X Server. Journaling is a technique that helps protect the integrity of HFS+
disks in RAID arrays. It limits the exposure for data loss and expedites repair if the
volume gets into an inconsistent state. Performance diminishes slightly when
journaling is on.
When you enable journaling on a volume, a continuous record of changes to files on
the volume is maintained in the journal. If your system stops running because of a
power failure or some other problem, when you restart the system the journal is used
to restore the volume to a known good state. Although you may experience loss of
user data that was buffered at the time of the failure, the file system is returned to a
consistent state. In addition, restarting the system is much faster.
You can also turn journaling on or off for a volume at any time in the Information
section of Disk Utility.
6 Type a name for the volume.
7 Click Erase and confirm your decision by clicking Erase again.
Once formatting is complete, the volume mounts on the host system.
Repeat this procedure for each new volume.
Note: If you want to add software RAID to two or more arrays, you can skip this
formatting procedure and instead use the RAID section of Disk Utility to stripe or mirror
the arrays together in a volume. This procedure also formats and mounts the resulting
volume. See “Adding Software RAID to Two or More Arrays” on page 21 for details.
Adding Software RAID to Two or More Arrays
Once you’ve set up arrays with RAID Admin, you can either stripe or mirror two
or more arrays using the Disk Utility application. Disk Utility is part of Mac OS X
(or Mac OS X Server) and is stored in the Utilities folder inside the Applications folder.
Use software stripe on RAID arrays to combine array capacities and improve
performance by taking advantage of multiple RAID controllers.
Use software mirror on RAID arrays to increase data protection through redundancy.
Note: You must use Disk Utility on the host computer to add software RAID to two
or more arrays.