Silicon Graphics Altix ICE 8000 Series, Краткое руководство пользователя

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1: SGI Altix ICE 8000 Series System Overview
Typically, each process of an MPI job runs exclusively on a processor. Multiple
processes can share a single processor, through standard Linux context switching, but
this can have a significant effect on application performance. A parallel program can
only finish when all of its sub-processes have finished. If one process is delayed
because it is sharing a processor and memory with another application, then the
entire parallel program is delayed. This gets slightly more complicated when systems
have multiple processors (and/or multiple cores) that share memory, but the basic
rule is that a process is run on a dedicated processor core.
Gigabit Ethernet Network
An Gigabit Ethernet connection network built into the backplane of the IRUs provides
a control network isolated from application data. Traverse cables provide connection
between IRUs and between racks. For more information on how the Gigabit Ethernet
connection fabric is used, see "VLANs" on page 16.
Individual Rack Unit
Each IRU has a one chassis management control (CMC) blade located directly below
compute blade slot 0 as shown in Figure 1-1 on page 2. This is the chassis manager
that performs environmental control and monitoring of the IRU. The CMC controls
master power to the compute blades under direction of the rack leader controller
(leader node). The leader node can also query the CMC for monitored environmental
data (temperatures, fan speeds, and so on) for the IRU. Power control for each blade
is handled by its Baseboard Management Controller (BMC), also under direction of
the rack leader controller. Once the leader node has asked the CMC to enable master
power, the leader node can then command each BMC to power up its associated
blade. The leader node can also query each BMC to obtain some environmental and
error log information about each blade.
The IRU provides data collected from compute nodes within the IRU to the leader
node upon request.
Power Supply
The CMC and BMCs are powered by what is called "AUX POWER". This power
supply is live any time the rack is plugged in and the main breakers are on. The
CMC and BMCs are
not able to be powered off under software control.
The compute blades have MAIN POWER which is controlled by the blade BMC. You
can send a command to the BMC and have the main power to the associated blade
turned on or off by that BMC.
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