Owners Manual

PS4100 Hardware Maintenance Guide Maintaining Control Modules
18
Single Controller Configuration
A single control module is a single point of failure. If the control module fails, the entire array (and all the
volumes on it) becomes unavailable. Dell strongly recommends buying an array with two control modules,
or installing a second control module in a single-controller array.
In an array with a single control module, the module must be in slot CM0.
Caution: For proper array cooling and airflow requirements, there must be a blank filler in the empty con-
trol module slot.
Dual Controller Configuration
A dual control module configuration eliminates a single point of failure in the array. If the active control
module fails, the secondary control module takes over immediately with no interruption of service. This
gives you time to replace the failed control module while your volumes and data remain accessible.
Interpreting Control Module LEDs
Control modules have the following LEDs:
• The Ethernet ports and the Management port each have two green LEDs that indicate the port's status
and activity.
• Below the release latch is a column of three LEDs that indicate the status of the entire control module.
Figure 14 Control Module LEDs