disk. The physical disk with the SMART error is marked as failed only after the successful completion of
the Replace Member. This prevents the array from reaching degraded state.
If an automatic Replace Member occurs using a source disk that was originally a hot spare (that was used
in a rebuild), and a new disk added for the Replace Member operation as the target disk, the hot spare
reverts to the hot spare state after a successful Replace Member operation.
NOTE: To enable the automatic Replace Member, use the Dell OpenManage storage management
application. For information on manual Replace Member, see Replacing An Online Physical Disks.
Patrol Read
The Patrol Read feature is designed as a preventative measure to ensure physical disk health and data
integrity. Patrol Read scans and resolves potential problems on configured physical disks. The Dell
OpenManage storage management application can be used to start Patrol Read and change its behavior.
The following is an overview of Patrol Read behavior:
•Patrol Read runs on all disks on the controller that are configured as part of a virtual disk, including
hot spares.
•Patrol Read does not run on physical disks that are not part of a virtual disk or are in Ready state.
•Patrol Read adjusts the amount of controller resources dedicated to Patrol Read operations based on
outstanding disk I/O. For example, if the system is busy processing I/O operation, then Patrol Read
uses fewer resources to allow the I/O to take a higher priority.
•Patrol Read does not run on any disks involved in any of the following operations:
– Rebuild
– Replace Member
– Full or Background Initialization
– CC
– RLM or OCE
NOTE: By default, Patrol Read automatically runs every seven days on configured SAS and SATA
hard drives. Patrol Read is not necessary on SSD and is disabled by default.
For more information on Patrol Read, see the Dell OpenManage documentation at dell.com/support/
manuals.
Physical disk failure detection
Failed physical disks are detected and rebuilds automatically start to new disks that are inserted into the
same slot. Automatic rebuilds can also occur with hot spares. If you have configured hot spares, the
controllers automatically try to use them to rebuild failed physical disks.
Using persistent hot spare slots
NOTE: The persistent hot spare slot feature is disabled by default.
The PERC 9 series can be configured so that the system backplane or storage enclosure disk slots are
dedicated as hot spare slots. This feature can be enabled using the Dell OpenManage storage
management application.
Once enabled, any slots with hot spares configured automatically become persistent hot spare slots. If a
hot spare disk fails or is removed, a replacement disk that is inserted into the same slot automatically
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