PS6610 Hardware Owner's Manual  3  Control Module Maintenance 
LED Name  State  Description 
Off  Normal operation or no power 
ERR 
Steady red 
Array is starting up, in error condition, in Standby mode, or returning from 
Standby mode. 
Blinking red 
Array is entering power standby mode because the Standby On/Off button 
was pressed. 
PWR 
Off 
On (steady 
green) 
No power 
Power/OK 
Identify Control Module Failures 
You can identify a failure in a control module by: 
•  LEDs on the control module itself. See Interpreting Control Module LEDs on page 16. 
•  Messages on the console, in the event log, or in the Group Manager GUI Alarms panel. 
•  Group Manager GUI and CLI output. The Member Controllers window or the 
member  select 
show  controllers 
command output shows the control module status not  installed. 
When viewed from the rear of the array, CM0 is on the left and CM1 is on the right. 
If a control module fails, contact your PS Series support provider for a replacement. 
About Failover Behavior 
In a dual control module array, only one control module is active (processing network I/O and 
performing storage functions) at one time. Each control module stores recently used data. 
For redundancy, the cache on the secondary control module mirrors the data that is stored in the cache 
on the active control module. 
The active control module can use the network interfaces of the secondary control module for failover 
if a cable is connected from the corresponding port on the secondary control module to a functioning 
network switch. 
Note:  The management ports on the control modules do not fail over if one control module fails. 
Therefore, if you are using a dedicated management network, make sure the management ports on 
both control modules are connected to the management network. 
A PS Series array provides the following types of network failure protection: 
•  Vertical failover. In a dual control module array, a network port on the active control module can 
fail over to the same network port on the other (secondary) control module if a network path fails. 
For example, if Ethernet 0 on CM0 loses connectivity (switch 0 fails), Ethernet 0 on CM1 cache is 
enabled and utilized. See Dual Controller Configuration on page 16 for details. 
•  Control module failover. In a dual control module array, if the active control module fails, the 
secondary control module automatically takes over and becomes active. 
If a cable is connected to a network port on the newly active control module, network I/O can 
switch to its network interface. Depending on circumstances, network I/O might instead continue 
through the previously active control module. (For example, the control module that becomes 
active can use either its own local network interface, or the network interface on the previously 
active control module.) 
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