Technical data

Hardware Overview

The modules communicate using the high-speed (1600 MB/sec) CrayLink Interconnect

link. The CrayLink Interconnect (also known as the interconnection fabric) link consists

of a set of high-speed routing switches and cabling that enables multiple connections to

take place simultaneously. Using the CrayLink Interconnect, hardware resources

(including main memory) can be shared and accessed by other modules in the

conﬁguration. For more information on the CrayLink Interconnect see “CrayLink

Interconnect” on page 11.

Note: Not all rack systems have two fully self-contained modules; some may have only

one; some conﬁgurations may have as many as 16 modules. For more information on the

different rack conﬁgurations, see Chapter 4, “System Conﬁgurations.”

Figure 1-5 provides an overall block diagram of an SGI 2400 server rack system. The

major hardware components include the:

• CPU and memory (Node) board

• Router board

• BaseIO board

• XIO slots

For a description of these components, see Chapter 2, “Chassis Tour.”

The rear module diagram shown in the top portion of Figure 1-5 appears in the back of

the chassis between the Node boards and fan tray. This diagram provides a map that tells

system installers where to install Node boards and XIO boards into the system. Use this

diagram to help correspond the Node boards and XIO blocks in the block diagram to

their actual physical location in the chassis. For more information on how to read this

diagram, see “Board Conﬁguration and Layout” on page 20 in Chapter 2.

Figure 1-6 shows how some of the major hardware components connect inside a system

module. All these components interface using a common midplane with connections

made to both the front and the back.