RAID 1(+0): breaking mirrors and rebuilding drives How to, 4th edition Abstract.............................. 2 Introduction............................2 Splitting a mirrored array using the Array Configuration Utility..............3 Recombining a split mirrored array using the Array Configuration Utility ............ 4 Breaking a mirror and rebuilding the array using the manual method ............5 Reverting to a previous copy of a mirrored set using the manual method ............
Abstract This paper explains two methods for safely breaking a RAID 1(+0) mirror and rebuilding drives in configurations with RAID1 (+0) volumes. The first method, using the HP Array Configuration Utility (ACU) split mirror feature, is available only while a server is offline and only for select controller models that may also require a valid HP Smart Array Advanced Pack license.
To split a mirrored array using the ACU, complete the following steps: Take the server offline. Insert the CD or bootable USB drive that contains the ACU (typically SmartStart) into any available media drive. Restart the operating system. Select the HP ACU selection within the Maintenance Operation menu. In the selection panel, select Array Configuration and Diagnostics.
CAUTION All data on the second array will be destroyed. Click OK. When ACU has finished updating the configuration, restart the operating system. The Smart Array controller will use the rebuild process to synchronize the mirrored drives. You can boot the operating system during the rebuild process, but the logical drive will not be fault-tolerant until the rebuild is complete.
NOTE For two-drive configurations, just remove one drive. For RAID 1+0 configurations, the first n/2 drives are always mirrored to the second n/2 drives (unless drives have been physically reordered using Offline Drive Movement). Do not remove drives that are mirrored to one another.
NOTE The drive-online LED will blink during the rebuild process. When it stops blinking and turns solid green, the rebuild is complete. A 300-GB SAS (3.5” 15K) drive can take up to 2 hours to rebuild a mirrored array (depending on the number of IOPS the server is submitting to the controller).
Figure 2. Boot-up message indicating no logical drives were found and that the backup drives are probably in the wrong drive bays During boot-up, the message will indicate that the drives are not responding (Figure 2). Press F2 to fail the missing drive and continue with one drive in recovery mode. Insert the drive to be overwritten into the open drive bay, and the array rebuild should start automatically.
For more information For additional information, refer to the resources listed below. Resource description Web address Business Support Center for HP Array http://h20000.www2.hp.com/bizsupport/TechSupport/Home.jsp?la Configuration Utility ng=en&cc=us&prodTypeId=18964&prodSeriesId=468780 http://h20000.www2.hp.com/bc/docs/support/SupportManual/c00 Configuring Arrays on HP Smart 729544/c00729544.pdf Array Controllers Reference Guide Call to action Send comments about this paper to TechCom@HP.com.