Users Guide

In the write-back policy, data is written to the cache before being written to the physical disk. If the virtual

disk goes offline or is deleted for any reason, the data in the cache is lost.

Data in the cache may also be lost in case of unintended cable or power failure. If such a failure, Storage

Management preserves the data written on the preserved or dirty cache until you recover the virtual disk

or clear the cache.

This feature is available only on SAS controllers with firmware version 6.1 and later.

The status of the controller is affected by the preserved cache. The controller status is displayed as

degraded if the controller has preserved cache.

CAUTION: You may not be able to use Storage Management to manage the preserved cache in

some cases. As an example, consider you have a RAID 1 level with two disks — D1 and D2. If you

now remove D2, the virtual disk is degraded and the data in the controller cache is written to D1.

So, D1 has the latest data. Now, if you re-insert D2 and pull out D1, the virtual disk is still

degraded and does not have the latest data.

You can discard the preserved cache only if all of the following conditions are met:

• The controller does not have any foreign configuration. Select Click for Preview to view details of the

foreign configuration. See Foreign Configuration Operations.

• The controller does not have any offline or missing virtual disks. If there are offline or missing virtual

disks, ensure that you have a backup of these virtual disks.

• Cables to any virtual disk are not disconnected.

Encryption Key

The controller uses the encryption key to lock or unlock access to SED. You can create only one

encryption key for each encryption-capable controller.

If you are using LKM, you must create the encryption key by providing the Encryption Key Identifier and

the Passphrase.

Encryption Key Identifier

An Encryption Key Identifier is a user-supplied text label for the Passphrase. The identifier helps you

determine which Passphrase to provide while authenticating import of foreign encrypted SED drives.

Passphrase

A Passphrase is a user supplied string that the controller uses to create the encryption key.

NOTE: For more information on Encryption Key and Passphrase guidelines, click the icon on

the Manage Encryption Key page.

Related Concepts

Managing The Encryption Key

Creating An Encryption Key And Enabling LKM

To create an encryption key on the selected controller:

1. Select the Enable Local Key Management (LKM) option.

2. Type Encryption Key Identifier.