HP Integrity rx4640 Server - Manual (Page 20)

Board Components and Features
• Auto-Reliability Monitoring (ARM) is a background process that scans hard
drives 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 drive failure
occurs in the future. ARM operates only when you select a fault-tolerant
configuration (RAID 1 or higher).
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Dynamic sector repair by the 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
hard drives, developed in collaboration with the hard drive industry. It monitors
several factors that can be used to predict imminent hard drive 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 drive sends an alert that failure is imminent. Thus, the user
can back up data and replace the drive before drive failure occurs.
NOTE: An online spare does not become active and start rebuilding when the imminent
failure alert is sent, because the degraded drive has not actually failed yet and is still
online. The online spare is activated only after a drive in the array has failed.
Drive failure alert features cause an alert message to be displayed on the
system monitor when drive failure occurs. Different server models use different
messages for different situations. These messages are described in your server
documentation.
Interim data recovery occurs if a drive fails in fault-tolerant configurations
(RAID 1 or higher). In this situation, the system will still 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. For example,
in a RAID 5 configuration, if another hard drive fails before data has been
rebuilt, the logical volume will fail and data will be lost. For more information
about recovering from drive failure, refer to Appendix E, “Hard Drive
Installation and Replacement.”
POST or the Array Diagnostics Utility will also reveal imminent drive failure.
HP Smart Array 5300 Controller User Guide 1-9
HP CONFIDENTIAL
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