HP A7143A RAID160 SA Controller Support Guide, February 2007

Hard Drive Installation and Replacement
Automatic Data Recovery
Appendix C
105
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.