VSP DRR Processors Test

A Data Recovery and Reconstruction Processor (DRR) is a microprocessor (located on the DKAs and channel adapters) 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 VSP storage device

Agent deploying the test : A remote agent

Outputs of the test : One set of results for every disk processor on the target Hitachi VSP device being monitored

The figure below depicts the test configuration page of this test. Click on the parameters in the figure below to know what they are and how to configure them.

Measures 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.