Dell PowerEdge RAID Controller H710 - Manual (Page 21)

of a virtual disk. The target disk needs to be a hot spare that qualifies as a rebuild disk. The physical disk with the
SMART error is marked as failed only after the successful completion of the Replace Member. This avoids putting the
array in degraded status.
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 for 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 .
NOTE: This support for redundant paths refers to path-redundancy only and not to controller-redundancy.
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