DRR Processors Test

A Data Recovery and Reconstruction Processor (DRR) is a microprocessor located on the DKAs that is used to generate parity data for RAID-5 or RAID-6 parity groups. The DRR uses the formula “old data + new data + old parity” to generate new parity.

This test monitors the usage of each DRR processor on the storage device, and reveals the over-utilized processors (if any).

Target of the test : A Hitachi USP storage device

Agent deploying the test : A remote agent

Outputs of the test : One set of results for every disk processor on the Hitachi USP device monitored.

Configurable parameters for the test
Parameter Description

Test Period

How often should the test be executed.


The IP address of the host for which this test is to be configured.


The port at which the specified host is listening. By default, this is set to NULL.

UserID, Password and Confirm password

The test should be configured with the credentials of a special user account, which is specifically created for use with the export utility; this account should fulfill the following conditions:

  • Should not possess the ‘write’ permission;
  • Can be of any user type; however, to ensure that the eG agent collects statistics pertaining to all storage partitions, it is recommended that this user is of type storage administrator;

Provide the credentials of this user against the UserID and Password parameters. Confirm the password by retyping it in the Confirm Password text box.


Specify the duration (in seconds) within which the SNMP query executed by this test should time out in this text box. The default is 5 seconds.

Measurements made by the test
Measurement Description Measurement Unit Interpretation

DRR processor usage

Indicates the percentage of time for which this DRR processor was in use.


A high value or a value close to 100% is indicative of a high write penalty condition. In such a case, you are advised to consult with your Hitachi Data Systems representative for for further information.

By comparing the value of this measure across processors, you can accurately detect imbalances in load distribution, and rapidly identify the affected DRR processors. To ensure that load is balanced within the subsystem, you might want to consider relocating volumes using Volume Migration.