HP A7143A RAID160 SA Controller Support Guide

Hard Drive Installation and Replacement
Automatic Data Recovery
Appendix C 147
Automatic Data Recovery
Automatic data recovery is an automatic background process that
rebuilds data onto a spare or replacement disk drive when another disk
drive in the array fails. This process is also called a rebuild.
If a disk drive in a fault-tolerant configuration is replaced while the
system power is off, a message is displayed during the next system
startup. This message informs you that an automatic data recovery
procedure has been initiated.
When automatic data recovery has finished, the Online LED of the
replacement drive stops blinking and begins to glow steadily.
In general, approximately 15 minutes is required to rebuild each
gigabyte. The actual rebuild time depends on:
• The level of rebuild priority that has been set for the logical drive
(saconfig automatically sets the priority to “high”)
• The amount of I/O activity occurring during the rebuild operation
• The disk drive speed
• The number of disks in the array (for RAID 5 and RAID ADG)
For example, the rebuild time when using 9-GB Wide-Ultra disk drives
in a RAID 5 configuration varies from ten minutes per gigabyte (for three
drives) to 20 minutes per gigabyte (for 14 drives).
Example C-2 Failure of Automatic Data Recovery
If the Online LED of the replacement disk drive stops blinking during
automatic data recovery, there are three possible causes:
• If the Online LED is glowing continuously, automatic data recovery
was successful and has finished.
• If the amber failure LED is illuminated or other LEDs go out, the
replacement disk drive has failed and is producing unrecoverable
disk errors. Remove and replace the failed replacement disk drive.
• If the automatic data recovery process has abnormally terminated,
one possible cause is a non-correctable read error on another physical
disk. Locate the faulty disk, replace it, and restore data from backup.