Each component
that goes into a server is designed to fulfill a specific requirement.
To allow multiple users, file server computers have a number of
special features. These special components allow a server to fulfill
its tasks to all users simultaneously.
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Server Chip Set |
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Multi-threading and simultaneous processing architecture |
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High availability power supplies |
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Redundant, multiple hard disks |
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Backup capability |
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Integrated network card |
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Sometimes multiple network cards or gigabit networking |
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Added cooling |
File server
hardware must have enough computing power to respond to the demands
of multiple users. For any server system you need at least:
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512 Mb of RAM (1-2 Gigs or more recommended) and should be ECC
error correcting code RAM. |
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20 Gig Hard disks (2 or more) preferably SCSI and 40 Gigs or
more each are preferable |
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An integrated network card |
Custom
built server features and terminology
Most
servers today are custom built to the customers specifications.
Lets look at what goes into making a server.
Server
Case
The Server
Case needs to provide sufficient space to hold your hard drives,
tape drives, and CD-ROMs. Except for very large companies, the server
case should hold all of your hard drives and still have room for
growth. The typical server case should hold between 10 and 20 drives.
The most common reason for electronic components failure is heat.
Every component in your server generates heat and lots of it. In
fact, all of those components inside your server can generate enough
heat to completely destroy your server without proper ventilation.
Today's high performance hard drive is spinning at 10,000 RPM and
requires direct cooling in order to maintain the drive warranty.
Our server cases have between 4 and 15 ventilation fans and we always
use direct cooling fans on hard drives.
High
Availability Power Supply
The power
supply(s) in the server has to be able to provide a lot more power
than a regular computer power supply A redundant power supply normally
consists of two or three hot-swap power supplies in one unit that
continuously supplies power to the server. In the event of a power
supply failure, the other power supply unit(s) will handle the full
load. The defective power supply unit can then be replaced without
turning off the server. There is typically an audible alarm that
alerts you that one of the power supplies is not functioning. Redundant
power supplies offer one other important feature, two power cords.
If the cords are plugged into different power sources, you can even
survive a tripped breaker or a cord accidentally disconnected.
Motherboard.
architecture and chipset
The motherboard
is what the actual computer chips, memory and other computer cards
plug into. It is the foundation of your server. Quality, features
and the ability to control each part of the motherboard varies widely
between motherboard manufacturers. Choosing the right motherboard
can save you money and allow your server to be expanded in the future.
Hard
Drives
Today
there are two types of hard drives, IDE and SCSI. Desktop computers
use IDE and servers use SCSI. SCSI drives are faster and smarter
and IDE drives are cheaper.
SCSI
Host Adapter
Hard drive
controllers or host adapters come in a wide range of features and
prices. Many motherboard companies provide a SCSI host adapter on
the motherboard. Each SCSI host adapters can control up to 15 hard
drives allowing room for expansion.
RAID
RAID is
a technology that allows us to arrange multiple hard drives together
to provide fault tolerance as well as very large logical drives.
The idea of fault tolerance allows us to have a single hard drive
failure without causing the server to fail. Here are two examples
of RAID:
RAID 1 or Mirroring
is where we take two hard drives of the same size and mirror all
information on both drives. If either one of these drives fail,
the system will keep going.
RAID 5
or Striping with parity allows us to take a number of smaller, less
expensive drives and make one large drive where you can have any
single drive in the array fail, without your server failing.
Software
and Hardware RAID
Some servers
have a specialized computer located right on the SCSI host adapter.
This is called hardware RAID. Some operating systems like Windows
NT and UNIX provide support for RAID in their operating systems
and don't require hardware to offer RAID.
So what is the
advantage of hardware RAID? Hardware RAID reduces the load on the
computer while software RAID consumes a significant portion of the
computing resources. Hardware RAID generally offers additional features
over software RAID. For instance, in the case of a hard drive failure,
hardware RAID can automatically take a hot spare drive and replace
the defective drive then rebuild the array. Hardware RAID does add
between $1,000 and $6,000 to your server, so choose wisely.
Tape
Drives
Tape backup
is your last line of defense in the case of disaster. Some of the
tapes should be stored off site in case of a disaster like fire
or flood. Studies show complete loss of data from a disaster is
enough to put many companies out of business. This can be even more
costly if the data you lose belongs to someone else.
NOS's
Think
of your NOS as a (very complex) tool. When you visit the hardware
store, how do you decide which tools to buy? With operating systems,
the same factors of function, brand name, purchase price, and expected
useful lifetime of the product apply. We should approach network
operating systems the same way we learn about many different types
of consumer products -- through research, talking to friends and
coworkers, and hands-on experimentation
Home network
users tend to require somewhat different features from the operating
system than corporate network managers, for example. However, some
common themes appear in most of the debates.
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