Users Guide

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 more information on automatic Replace Member, see the topic Dell OpenManage
Storage Management. For information on manual Replace Member, see the topic Replacing An
Online Physical Disk.
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.
Redundant Path Support (For PERC H810 Only)
The PERC H810 adapter can detect and use redundant paths to disks contained in enclosures. This
provides the ability to connect two SAS cables between a controller and an enclosure for path
redundancy. The controller is able to tolerate the failure of a cable or Enclosure Management Module
(EMM) by utilizing the remaining path.
When redundant paths exist, the controller automatically balances I/O load through both paths to each
disk. Load balancing increases throughput to virtual disks in storage enclosures and is automatically
turned on when redundant paths are detected. The ability to load balance I/O can be disabled using the
Dell OpenManage storage management application.
To set up your hardware to support redundant paths, see the topic Setting Up Redundant Path Support
On The PERC H810 Adapter.
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