NonStop NS-Series Planning Guide (H06.03+)

Control, Configuration, and Maintenance Tools
HP Integrity NonStop NS-Series Planning Guide—529567-004
5-6
Fabrics Functional Element
Fabrics Functional Element
The p-switch module contains the functionality of a single-fabric functional element.
Each of the p-switches in the system provides a single-fabric ServerNet interconnect to
processor functional elements, IOAMs, and NonStop S-Series I/O enclosure.
Each p-switch contains a single ME that controls only its internal hardware. The p-
switch provides a communications mechanism to interact with logical processors, but it
does not control, report, or track any attributes within the hardware that makes up a
logical processor (PEs, slices, processor complexes, or LSUs).
P-Switch ME Firmware
ME firmware executes on the microprocessors within the ServerNet switch board that
is implemented with each p-switch (see Processor Switch on page 2-13) and with each
of the two IOAM modules within the IOAM enclosure (see I/O Adapter Module (IOAM)
Enclosure and I/O Adapters on page 2-17). However, maintenance firmware within a
slice, LSU, or disk drive enclosure is separate and has no direct interaction with the
ME firmware.
When it is executing within a p-switch, the ME firmware initializes, controls, and
monitors its elements that are local to that p-switch. No direct connection exists to the
other p-switch in the system, so the ME firmware on a given p-switch has no hardware
responsibilities in terms of its peer p-switch.
The ME firmware on a p-switch provides a logical communications interface to each of
the directly connected processors (either the HSS or OS, depending on the state of the
processor) via the ServerNet links. The ME firmware also tracks the presence or
absence of each of the directly connected processors so that external client
applications can obtain the system hardware configuration and state.
In addition to hardware control, p-switch ME firmware:
•
Establishes ME-to-processor communication interface (SMIP)
•
Provides system configuration tables to the OS during coldload
•
Provides SPIOLib focal point for OS clients and LAN-based MCA clients
•
Provides ME subsystem events to the OS clients
All of these essentials that the p-switch provides for the processors involve persistent
state and a single point of control. Because OS clients can attach to either of the two p-
switches, the ME firmware operates in a primary versus secondary execution state
between peer p-switch ME applications.
At any given time, only one p-switch ME firmware application between peer modules is
in a primary state and is responsible for processor essentials. If a p-switch ME
application executing in the secondary state receives a request for a service that only a
primary can honor, the secondary routes the request via the ServerNet to the primary
ME applications for execution. This routing is automatic, with no intervention required
from the OS or client applications.