User manual APPLE RAID UTILITY

[. . . ] 4 In RAID Utility, use the Create RAID Set and Create Volume commands to create your RAID volumes. For information, see "Creating a RAID Set" on page 8, and "Creating a Volume" on page 9. 6 Follow the Installer onscreen instructions to install Mac OS X or Mac OS X Server on one of the new RAID volumes and restart the computer. 5 Migrating an Existing Volume to a RAID Volume When you purchase a computer with the RAID card installed, the startup disk is configured as a single-disk Enhanced JBOD RAID set. You can convert this RAID set, along with one, two, or three empty disks, to a RAID volume in one step using the Migrate RAID Set command. [. . . ] If the verification process reports problems, you can use the command $ raidutil modify volume --rewrite in Terminal to recreate the volume's data protection information. For information, see the raidutil man page or type raidutil at the command-line prompt. If Write Caches are Disabled The RAID card backup battery may not be fully charged. To protect your data, the RAID card automatically disables write caching whenever the battery is not fully charged. Once every three months the RAID card reconditions the battery by completely discharging and then recharging it. If the Battery is Not Fully Charged Every three months, the RAID card automatically reconditions its battery by completely discharging and then recharging it. During the reconditioning cycle, you may see an alert advising you that the 72-hour battery reserve is unavailable and the controller status may indicate that write caches are disabled. Performance may be slightly degraded during this time, but will return to normal when the battery is recharged. If you are using SAS drives, SMART is listed as unsupported in the drive information in RAID Utility. 13 Viewing the RAID System Log If you have trouble with your RAID configuration, you can check the diagnostic messages in the RAID log for more information. The RAID card and associated software write status and diagnostic messages to /Library/Logs/CoreRAID. log. To view the RAID log: 1 Open the Console application (in /Applications/Utilities/). 3 Choose /Library/Logs/CoreRAID. log from the list on the left. Using the Command Line You can also set up and manage your RAID card from the command line using the raidutil command. For information, see the raidutil man page or type raidutil at the command-line prompt. 14 About RAID Levels RAID Utility lets you set up RAID sets based on the following RAID levels: Â Enhanced JBOD Â RAID 0 (striping) Â RAID 1 (mirroring) Â RAID 0+1 (mirroring a striped pair) Â RAID 5 (striping with distributed parity) Enhanced JBOD Using Enhanced JBOD, you can create a RAID set using a single drive. The resulting RAID set doesn't gain the performance or data protection of the other RAID levels, but it does benefit from the data caching and battery backup provided by the RAID card. An enhanced JBOD set can also be migrated to other RAID sets or moved to another computer that has a Mac Pro or Xserve RAID Card installed. RAID 0 RAID 0 offers improved performance but no data protection. Blocks of data are spread across all of the drives in the RAID set in a process called striping. This allows better performance because file contents move in parallel to and from the individual drives in the set. RAID 0 also provides the most usable disk space; nearly all space on all drives is available for user data. You can create a RAID 0 set using two, three, or four disks. RAID 1 RAID 1 protects data against a drive failure and allows some increase in read performance. Data is protected by duplicating the contents of each drive on a second drive in the set, a process called mirroring. Because of the duplication, a volume based on a RAID 1 set can't be larger than half of the total space available on the drives in the set. You can create a RAID 1 set using either two or four disks. RAID 0+1 RAID 0+1 combines the performance of RAID 0 with the data protection of RAID 1 by mirroring a striped set on a second pair of drives. Because mirroring duplicates all data, this level offers less usable disk space than RAID 5. Usable space is half of the total space available on the drives in the set. [. . . ] The result is a fast 1, 500 GB data volume that is independent of the computer's startup disk. Creating a New Startup Volume and Several Data Volumes In this example, you'll recreate a startup volume, add several data volumes, and save some space for a future volume, all on a protected RAID set that has a spare drive available. As in the previous two examples, we'll assume that you've purchased a computer with a RAID card and four 500 GB disk drives. To set up this example: Because you're going to recreate the current startup disk, you need to restart the computer using the installation disc that comes with your computer and open RAID Utility from the Utilities menu. Next, for the protection of the new startup disk and the data volumes, you create a single RAID 5 set. [. . . ]