Compaq ProLiant 4000 SMART-2DH Array Controller Reference Guide - Page 155
Interim Data Recovery, Automatic Data Recovery, In general
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D-22 Understanding Drive Arrays Interim Data Recovery In RAID 5, RAID 4, or RAID 1 fault-tolerant configurations, if a drive fails, the system continues to operate in an interim data recovery mode. For example, if you had selected RAID 5 for a logical drive with four physical drives and one of the drives fails, the system continues to process I/O requests, but at a reduced performance level. Replace the failed drive as soon as possible to restore performance and full fault tolerance for that logical drive. Refer to Appendix G for more information on recovering from drive failure. Automatic Data Recovery After you replace a failed drive, automatic data recovery reconstructs the data and places it on the replaced drive. This allows a rapid recovery to full operating performance without interrupting normal system operations. In general, the time required for a rebuild is approximately 15 minutes per gigabyte. The actual rebuild time however is dependent upon the rebuild priority set for the amount of I/O activity occurring during the rebuild operation and upon disk drive speed, and the number of drives in the array (RAID 4 and RAID 5). In RAID 4 and RAID 5 configurations, the rebuild time varies from 10 minutes/GB for three drives to 20 minutes/GB for 14 drives (using 9-GB wide-ultra hard drives). NOTE: You must specify RAID 5, RAID 4, or RAID 1 through the Array Configuration Utility to make the recovery feature available. The drive failure alert system and automatic data recovery are functions of the SMART-2DH Controller; they operate independently of the operating system. Writer: Pamela King Project: SMART-2DH Array Controller Reference Guide Comments: 295469-002 File Name: K-APPD.DOC Last Saved On: 2/27/98 12:06 PM COMPAQ CONFIDENTIAL - NEED TO KNOW REQUIRED