HP BladeSystem c-Class architecture Technology brief, 4th edition

Scalable interconnect form factors

The interconnect bays also scale in a single-wide and double-wide form factor for efficient use of

space and improved performance. A single interconnect bay can accommodate two single-wide

interconnect modules in a scale-out configuration or a larger, higher-bandwidth double-wide

interconnect module (Figure 5).

Figure 5: Single-wide and double-wide interconnect form factors

The scalable interconnect form factor provides similar advantages as the scalable device bays:

• It supports the maximum number of interconnect modules.

• It allows enough space in a double-wide module to include two signal connectors on the same PCB

plane. This affords reliable and simple connectivity to the NonStop signal midplane.

Star topology

The device bays and interconnect bays connect in a fan-out, or star, topology centered around the

interconnect modules. The exact topology depends on your configuration and the enclosure. For

example, if you place two single-wide interconnect modules side-by-side (Figure 6a), the architecture

is a dual-star topology. Each blade has redundant connections to the two interconnect modules. If you

use a double-wide interconnect module, it is a single star topology, providing more bandwidth to

each server blade. Figure 6b shows the redundant configuration using double-wide interconnect

modules.

Figure 6: The blade-to-interconnect topology differs depending on your configuration.

6a 6b

blades

Interconnect Module B

blades

Interconnect Module A

Interconnect

Module A

Interconnect

Module B