Software Support

Setting The Patrol Read Mode
Does my controller support this feature? See Supported Features.
Patrol read identifies disk errors in order to avoid disk failures and data loss or corruption. The Set Patrol Read task is
applicable only for disks used as virtual disks or hot spares.
The Set Patrol Read tasks run in the background and corrects, when possible. When the Set Patrol Read mode is set to
Auto, patrol read is initiated when the controller is idle for a period of time and when no other background tasks are
active. In this scenario, the patrol read enhances the system performance as disk errors can be identified and corrected
when there is not input/output activity on the disk.
The controller adjusts the amount of system resources dedicated for patrol read based on the amount of controller
activity that is competing with the Patrol Read task. When the controller activity is high, fewer system resources are
dedicated to the patrol read task.
Patrol Read does not run on a physical disk in the following circumstances:
• The physical disk is not included in a virtual disk or is assigned as a hot spare.
• The physical disk is included in a virtual disk that is currently undergoing one of the following:
– Rebuild
– Reconfiguration or reconstruction
– Background initialization
– Check consistency
In addition, the Patrol Read suspends during heavy I/O activity and resumes when the I/O is finished.
Related Links
Starting And Stopping Patrol Read
To Set The Patrol Read Mode
Select the desired Patrol Read Mode option. The options available are:
• Auto — Initiates the Patrol Read task. After the task is complete, it automatically runs again within a specified
period. For example, on some controllers the Patrol Read runs every four hours and on other controllers, the
Patrol Read runs every seven days. The Patrol Read task runs continuously on the system starting again within
the specified period after each iteration of the task completes. If the system reboots while the Patrol Read task
is running in Auto mode, the Patrol Read restarts at zero percent (0%). When the Patrol Read task is set to Auto
mode, you cannot start or stop the task. Auto mode is the default setting.
NOTE: For more information on how often the Patrol Read task runs when in Auto mode, see your controller
documentation.
• Manual — Enables you to start and stop the Patrol Read task using Start and Stop Patrol Read. Setting the mode
to Manual does not initiate the Patrol Read task. If the system reboots while Patrol Read is running in Manual
mode, Patrol Read does not restart.
• Disabled — Prevents the Patrol Read task from running on the system.
To Locate Set Patrol Read Mode In Storage Management
1. In the Server Administrator window, under the system tree, expand Storage to display the controller objects.
2. Select a controller object.
3. Click Information/Configuration on the controller Properties page.
4. Select Set Patrol Read mode from the Available Tasks drop-down menu.
5. Click Execute.
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