Users Guide

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 and later of 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 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 operations are possible while the background initialization
is running. However, other processes such as creating a virtual disk, cannot be run concurrently with background initialization.
These processes cause the background initialization to cancel.
Non-RAID Controller Description
The non-RAID SCSI and SAS controllers are non-RAID controllers that support SCSI and SAS devices. Because these controllers
are non-RAID, they do not support virtual disks. You can manage these non-RAID controllers and their attached SCSI and SAS
devices with Storage Management.
NOTE: Supported features may vary from controller to controller.
Non-RAID SAS Controllers
The following non-RAID controllers use Serial Attached SCSI (SAS) technology:
● SAS 12 Gbps HBA
● HBA 330
● HBA 330MX
● HBA 330MMZ
Controllers
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