376
Networking Fundamentals
fi rmware
the combination of
BIOS chip and the
software program
within the chip.
power-on self-test
(POST)
a BIOS routine that
performs a series
of hardware checks
to determine if
the computer is in
minimal working
order.
parallel processing
processing a
program through
more than one CPU
simultaneously.
numerous network clients with minimal delay. The CPUs need not be the latest, high-
speed processors available because there are numerous processors in the server.
BIOS
The BIOS contains a small software program that starts the server boot
operation when power is applied to the server. The combination BIOS chip and
the software program are usually referred to as fi rmware. The BIOS is responsible
for the power-on self-test (POST), which is performed at startup. The POST
does a quick, initial check of the major components, such as memory, disk drives,
keyboard, mouse, and monitor, to be sure that a minimum working system is
available. After a general check is made of the major hardware components, the
BIOS turns control over to the operating system software. The operating system
completes the boot process by loading more advanced hardware drivers than the
BIOS did. It also performs a more sophisticated check of hardware and software
systems. If all the software and hardware components appear to be in working
order, the fi nal screen, which serves as a user interface, appears.
Central Processing Unit (CPU)
One major difference between a server and a typical PC is that many
servers have multiple CPUs installed rather than just one. When multiple CPUs
are installed, the server can perform parallel processing. This means that a
program can be processed through more than one CPU simultaneously. Another
advantage of multiple CPUs is several clients may be serviced at the same time
rather than waiting their turn to access a single CPU. Supercomputers and
enterprise servers may contain over 1,000 CPUs.
A small offi ce server can get by with one processor, especially if demand on
the server is low. A large enterprise system requires multiple processors to meet
the demands of the server’s clients. Some processor modules are hot-swappable.
When a single CPU fails, it can easily be removed and replaced while the server
is running and providing services to clients.
Figure 9-6.
The backplane layout of the ProLiant DL740.
Memory
module
1
Memory
module
2
Memory
module
3
Memory
module
4
Memory
module
5
Processor
board
2
Processor
board
1
I/O board with
6 PCI hot plug
slots
Fan
2
Fan
1
Fan 1
connector
Memory
module 1
connector
Memory
module 2
connector
Memory
module 4
connector
Memory
module 3
connector
Memory
module 5
connector
Processor
board 2
connector
Processor
board 1
connector
I/O board
connector
Fan 2
connector
Backplane Backplane with modules and I/O board