HP A7143A RAID160 SA Controller Support Guide

RAID160 SA Controller Overview
Board Components and Features
Chapter 2 33
Fault Management Features
The RAID160 SA controller and the HP-UX operating system support
several fault management and data reliability features that minimize
the impact of disk drive defects on your system.
• Auto-Reliability Monitoring (ARM) is a firmware process that
operates in the background scanning physical disks for bad sectors in
fault-tolerant logical drives. ARM also verifies the consistency of
parity data in logical drives that are using RAID 5 or RAID ADG.
This process assures that you can recover all data successfully if a
disk failure occurs in the future. ARM operates only when you select
a fault-tolerant configuration (RAID 1 or higher).
• Dynamic sector repair by the RAID160 SA controller
automatically remaps any sectors that have media faults (detected
either during normal operation or by auto reliability monitoring).
• S.M.A.R.T. is an industry-standard diagnostic and failure-prediction
feature of physical disks, developed by HP in collaboration with the
disk drive industry. It monitors several factors that can be used to
predict imminent physical disk failure due to mechanical causes.
Such factors include the condition of the read/write head, the seek
error rate, and the spin-up time. When a threshold value is exceeded
for one of these factors, the disk sends an alert that failure is
imminent. Thus, the user can back up data and replace the disk
drive before failure occurs.
NOTE An online spare does not become active and start rebuilding when
the imminent failure alert is sent, because the degraded disk has not
actually failed yet and is still online. The online spare is activated
only after a disk in the array has failed.
• Drive failure alert features cause an alert message to be sent to
Event Monitoring Services (EMS) when physical disk or logical drive
failure occurs.
• Interim data recovery occurs if a disk fails in fault-tolerant
configurations (RAID level 1 or higher).