Users Guide

Secure firmware update

This feature provides a cryptographic method of updating the firmware using an RSA encryption-decryption algorithm.

Only Dell-certified firmware is supported on your PERC controller.

Snapdump

The Snapdump feature provides the Dell support team with the debug information which can help to find the cause of firmware

failure. In the instance of firmware failures, the firmware collects the logs and information at the time of failure, which are

stored in a compressed file called a snapdump.

Snapdumps are also generated manually to provide additional debug information. When a snapdump is generated, it is stored in

the controller's cache memory. This means in the event of a power loss the controller will offload the snapdump as part of its

cache preservation mechanism. Snapdumps are preserved by default through four reboots before its deleted.

To generate a snapdump, change the snapdump, delete a snapdump, and to download a stored snapdump settings, see Dell

EMC PowerEdge RAID Controller CLI Reference Guide at www.dell.com/storagecontrollermanuals.

Virtual disk features

This section lists the following virtual disk features supported on PERC 11 cards in detail:

● Virtual disk write cache policy

● Virtual disk read cache policy

● Virtual disk migration

● Virtual disk initialization

● Reconfiguration of virtual disk

● Background operations

Virtual disk write cache policy

The write cache policy of a virtual disk determines how the controller handles writes to the virtual disk.

Table 4. Write cache policies

Feature Description

Write-back The controller sends a data transfer completion signal to the host when the controller cache

has received all the data in a transaction. The controller then writes the cached data to the

storage device in the background.

NOTE: The default cache setting for virtual disks is Write-back caching. Write-back

caching is also supported for single drive RAID 0 virtual disks.

Write-through The controller sends a data transfer completion signal to the host system when the disk

subsystem has received all the data in a transaction.

NOTE: Certain data patterns and configurations perform better with a write-through

cache policy.

NOTE: All RAID volumes are presented as write-through to the operating system (Windows and Linux) independent of the

actual write cache policy of the virtual disk. PERC cards manage the data in cache independently of the operating system or

any applications.

NOTE: Use the Dell OpenManage storage management application or the HII Configuration Utility to view and manage

virtual disk cache settings.

Conditions under which write-back is employed

Write-back caching is used under all conditions in which the battery is present and in good condition.

Features of PowerEdge RAID Controller 11