Control Module Description; About Control Module Configurations - Dell EqualLogic PS-M4110 Hardware Owner's Manual

Dell EqualLogic PS-M4110 Hardware Owner's Manual

Control Module Description

The PS-M4110 uses a Type 13 control module that includes:
• Ethernet port - A 10Gb/s iSCSI Ethernet port (Ethernet 0) for communication on one of two redundant fab-
rics.
• Management port - Ethernet port 1 can optionally be set up as a management port.
• Status and Power LEDs - Indicate status of the control module. ACT LED for activity and PWR LED for
power.
• Serial port - The serial port on the front of the array connects to the control module so you can connect a
computer directly to the array, without network access.
• microSD card - A field-replaceable microSD card containing the PS Series firmware.
• Release button and latch - Releases the control module from the array for replacement.
Do not mix control module types in an array. Always make sure both control modules are the same type and
color. See the latest PS Series Release Notes for information about other supported control modules.

About Control Module Configurations

While an array can run using only one control module, it is not recommended because this creates a single point
of failure. If a control module fails and a secondary is not available to take over, all access to your volumes
stops until you replace it.
Do not mix control module types in an array. Always make sure both control modules are the same type.
Only one control module is active and serving network traffic at a time. The secondary (redundant) control
module mirrors cache data from the active control module. If the active control module fails, the secondary will
take over network operations.
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 control module filler in the
empty control module slot.
36
Chapter 4 Maintaining Control Modules