Users Guide

controller. This feature is not dependent on the controller mode and can function as usual when the
controller is running in RAID or HBA mode.
Set the physical disk caching policy of all members of a virtual disk by enabling the Disk Cache Policy.
When this feature is enabled, the physical disk writes data to the physical disk cache before writing it to
the physical disk. Because it is faster to write data to the cache than to a disk, enabling this feature
improves system performance.
The following are the disk cache policy options for Non-RAID disks connected to a PERC hardware
controller:
• Enabled — Disk Cache Policy is enabled.
• Disabled — Disk Cache Policy is disabled.
• Unchanged — The disk uses the default write cache mode.
NOTE: The Unchanged option is applicable only for PERC 9 hardware controllers with the latest
firmware version.
NOTE: If you want to revert the Disk Cache Policy settings of the physical disks to the factory
default settings, then you must restart the server.
The following are the disk cache policy options for RAID disks connected to Software RAID S130
controller:
• Default — The disk uses the default write cache mode.
• Enabled — Disk Cache Policy is enabled.
• Disabled — Disk Cache Policy is disabled.
• Inconsistent — The disk cache policy is not uniform across all the physical disks in the virtual disk. For
example, if a virtual disk contains three physical disks; the disk cache policy of the first physical disk is
Enabled, the second physical disk is Disabled, and the third physical disk is Default. Then the disk
cache policy state for the virtual disk is displayed as Inconsistent.
NOTE: The default setting for Disk Cache Policy for virtual disks based on SATA drives is Enabled,
and for virtual disks based on SAS drives is
Disabled.
NOTE: For SAS 6i/R and PERC H200 family of controllers, the Disk Cache Policy setting is available
only after creating the virtual disk.
Related Task
• Changing The Virtual Disk Policy
Background Initialization On PERC Controllers
On PERC controllers, background initialization of a redundant virtual disk begins automatically within 0 to
5 minutes after the virtual disk is created. The background initialization of a redundant virtual disk
prepares the virtual disk to maintain redundant data and improve write performance. For example, after
the background initialization of a RAID 5 virtual disk completes, the parity information is initialized. After
the background initialization of a RAID 1 virtual disk completes, the physical disks are mirrored.
The background initialization process helps the controller identify and correct problems that may occur
with the redundant data later. In this regard, the background initialization process is similar to a check
consistency.
The background initialization should be allowed to run to completion. If canceled, the background
initialization automatically restarts within 0 to 5 minutes. Some processes such as read and write
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