Compaq Infortrend manual B. Controller Failover and Failback, C. Active-to-Active Configuration

B. Controller Failover and Failback

In an unlikely event of controller failure, the surviving controller will acknowledge the situation and disconnect with the failed controller. The surviving controller will then behave as both controllers and serve all the host I/O requests.

System failover is transparent to host. System vendors should be contacted for an immediate replacement of the failed unit.

Replacing a Failed Unit:

The replacement controller should have the same amount of memory and the same version of firmware installed. However, it is inevitable a replacement controller is usually running later revisions of firmware. To solve this problem, Firmware Synchronization is supported since firmware version 3.21. When the replacement controller is combined, the existing controller will downgrade the replacement’s firmware so that both controllers will be running the same version of firmware.

Your system vendor should be able to provide an appropriate replacement controller.

Auto-Failback:

Once the failed controller is removed and a replacement controller is installed, the existing controller will acknowledge the situation. The existing controller will automatically combine with the replacement controller.

When the initialization process of the replacement controller is completed, the replacement controller will always inherit the status of the Secondary controller. The replacement controller will obtain all related configuration parameters from the existing controller. If the existing controller fails to re-establish this connection, you can also choose to "de-assert" the replacement controller through the existing controller so that both will serve the original system drive mapping.

C. Active-to-Active Configuration:

Active-to-active configuration conducts all system resources to performance. Storage volumes can be equally assigned to both controllers and thus both are actively serving I/Os. This allows a flexible association between logical units and host ID/LUNs. Workload can then be manually distributed between controllers.

Redundant Controller 10-11