IBM PureFlex System and IBM Flex System Products and Technology

72 IBM PureFlex System and IBM Flex System Products and Technology

򐂰 Check Error Log LED: When lit (amber), this LED indicates that a noncritical event has

occurred. This event might be a wrong I/O module inserted into a bay, or a power

requirement that exceeds the capacity of the installed power modules.

򐂰 Fault LED: When lit (amber), this LED indicates that a critical system error has occurred.

This can be an error in a power module or a system error in a node.

Figure 4-16 shows the LEDs on the rear of the chassis.

Figure 4-16 Chassis LEDs on the rear of the unit (lower right)

4.6 Cooling

This section addresses Enterprise Chassis cooling. The flow of air within the Enterprise

Chassis follows a front to back cooling path. Cool air is drawn in at the front of the chassis and

warm air is exhausted to the rear. Air is drawn in both through the front node bays and the

front airflow inlet apertures at the top and bottom of the chassis. There are two cooling zones

for the nodes: A left zone and a right zone.

The cooling can be scaled up as required, based on which node bays are populated. The

number of fan modules required for a certain number of nodes is described further in this

section.

When a node is not inserted in a bay, an airflow damper closes in the midplane. Therefore, no

air is drawn in through an unpopulated bay. When a node is inserted into a bay, the damper is

opened mechanically by the node insertion. This action allows for cooling of the node in that

bay.

Identify

LED

Check

log

LED

Fault

LED

73

Figure 4-17 shows the upper and lower cooling apertures.

Figure 4-17 Enterprise Chassis lower and upper cooling apertures

Various fan modules are present in the chassis to assist with efficient cooling. Fan modules

consist of both 40 mm and 80 mm types, and are contained within hot pluggable fan modules.

The power supplies also have two integrated, independently powered 40 mm fan modules.

The cooling path for the nodes begins when air is drawn in from the front of the chassis. The

airflow intensity is controlled by the 80 mm fan modules in the rear. Air passes from the front

of the chassis, through the node, through openings in the Midplane and then into a plenum

chamber. Each plenum is isolated from the other, providing separate left and right cooling

zones. The 80 mm fan packs on each zone then move the warm air from the plenum to the

rear of the chassis.

In a 2-bay wide node, the air flow within the node is not segregated because it spans both

airflow zones.

Upper cooling apertures

Lower cooling apertures

74 IBM PureFlex System and IBM Flex System Products and Technology

Figure 4-18 shows a chassis with the outer casing removed for clarity to show airflow path

through the chassis. There is no airflow through the chassis midplane where a node is not

installed. The air damper is opened only when a node is inserted in that bay.

Figure 4-18 Airflow into chassis through the Nodes and exhaust through the 80 mm fan packs (chassis

casing is removed for clarity)

Node installed in Bay 1

80 mm fan pack

Node installed in Bay 14

Cool airflow in

Warm Airflow

Midplane

Cool airflow in

75

Figure 4-19 shows the path of air from the upper and lower airflow inlet apertures to the

power supplies.

Figure 4-19 Airflow path power supplies. (chassis casing is removed for clarity)

Power Supply

Cool airflow in

Nodes

Midplane

Cool airflow in