Users Guide

Table Of Contents
NOTE: To enable automatic replace member, use the Dell OpenManage storage management application.
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.
The amount of controller resources dedicated to patrol read operations adjusts based on the number of outstanding disk I/O
operations. For example, if the system is processing a large number of I/O operations, then patrol read uses fewer resources
to allow the I/O to take a higher priority.
Patrol read does not run on disks that are 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.
For more information about patrol read, see the Dell OpenManage documentation at www.dell.com/openmanagemanuals.
Physical disk failure detection
If a disk fails and it is replaced with a new disk, the controller will automatically start a rebuild on the new disk. See,
Configured slot behavior. Automatic rebuilds can also occur with hot spares. If you have configured hot spares, the controller
will automatically try to use them to rebuild the degraded virtual disk.
Using persistent hot spare slots
NOTE: The persistent hot spare slot feature is disabled by default.
The PERC 10 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 becomes a hot spare with the same properties as
the one it is replacing. If the replacement disk does not match the disk protocol and technology, it does not become a hot spare.
For more information on persistent hot spares, see the Dell OpenManage documentation at www.dell.com/openmanagemanuals.
Configured slot behavior
This feature is similar to persistent hot spare slot behavior. If a redundant VD is configured to the system and if a drive is
replaced, the configured slot will automatically rebuild or copyback on the inserted drive regardless of the data on the drive. This
operation will overwrite the data on the drive.
Table 6. Drive state/operation
Drive state/operation Unconfigured
slot
Slot configured in VD
Insert unconfigured drive into the system Ready Rebuild or copyback start
Insert configured drive into the system Foreign Rebuild or copyback start
Original drive data lost
Features 29