Dell PowerEdge RAID Controller 10 User’s Guide PERC H345, H740P, H745, and H840 Series Controllers

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.