HP ProLiant DL740 Server - Manual (Page 127)

Installing Hardware Options, Hot-Plug
Advanced Data Guarding
When a hot-pluggable disk drive is removed, although the system is functionally
operational, the disk subsystem may no longer be fault tolerant. Fault tolerance will
be lost until the removed drive is subsequently replaced and the rebuild operation is
completed. This procedure takes several hours, even if the system is not busy while
the rebuild is in progress. If another drive in the array should incur an error during the
period when fault tolerance is unavailable, a fatal system error could result. If another
drive fails during this period, the entire array contents will be lost.
IMPORTANT: Perform disk drive replacement during low activity periods whenever possible.
In addition, a current valid backup of the logical drives in the array of the drive being replaced
should be available even if the drive replacement is being made during server downtime.
When replacing hot-plug hard drives in a fault-tolerant configuration, you must
follow these guidelines:
• Never remove more than one drive at a time. When a drive is replaced, the
controller uses data from the other drives in the array to reconstruct data on the
replacement drive. If more than one drive is removed, a complete data set is not
available to reconstruct data on the replacement drive.
• Never remove a working drive when another drive has failed. Drives that
have been designated as failed by the controller are indicated by the amber Drive
Failure LED on the drive tray. Permanent data loss will occur if a working drive
is removed while a failed drive is being replaced.
• Never remove a drive while another drive is being rebuilt. The Online LED
on a drive will flash green while it is being rebuilt. A replaced drive is restored
from data stored on the other drives.
5-28 HP ProLiant DL740 Server User Guide
HP CONFIDENTIAL
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