NonStop S-Series Server Description Manual (G06.27+)

Introduction

HP NonStop S-Series Server Description Manual—520331-004

1-18

Expansion to External I/O Enclosure

ServerNet expansion boards (SEBs) provide router ports that can exand to I/O

enclosures as well as to other processor enclosures (as in the preceding topic).

There are two significantly different methods of providing external I/O. One method

uses the I/O enclosures that have the standard system enclosure design, as shown in

the first three figures of this section. This method of I/O expansion is described first.

The other method, modular I/O, uses a different architecture and a different form factor

for external cabinets, and is described later. See Modular I/O on page 1-38.

Figure 1-10 shows expansion from one processor enclosure to one I/O enclosure. In

this case, three of the SEB router ports are used, and three are unused.

Figure 1-10 assumes that the second processor enclosure is still connected to the

same router ports (X and Y) of the first processor enclosure. However, the internal

details of that second enclosure are not shown here.

As before, the ServerNet cables between enclosures are represented by bold lines.

Note that, in the I/O enclosure, the cable does not connect to another SEB but instead

the ServerNet lines are routed through a ServerNet buffer board (SBB) to a

multifunction I/O board (MFIOB). (SEBs are not supported in I/O enclosures.) The

SBB physically does not occupy the position of an SEB but rather is part of the I/O

multifunction (IOMF) CRU, as shown in the next topic.

The internal arrangement of the X and Y routers in the I/O enclosure is similar to that in

a processor enclosure, but only six-port routers are currently supported.

However, note that, because there are no router connections to processors, two

additional router ports are available for I/O connections. (Compare MFIOBs in the two

enclosures.) Five of the MFIOB router ports are available for internal I/O. The two

additional ports are used for two additional ServerNet adapters, so that each I/O

enclosure can support four ServerNet adapters, rather than just two in the case of

processor enclosures.