VITTA Networking CD - technologies

networking curriculum
support CD for senior
secondary studies

Topics
. Home
. Networking History
. Why network?
. OSI model
. Connecting up
. Protocols
. Technology
. Network types
. Topologies
. Issues
. Design factors
. Economic effects
. www links
. Site map

networking > technologies > servers

Servers

Servers (including file servers, application servers, proxy servers, web servers etc) are not significantly different in nature to the average computer, but they must be more powerful and robust because they become the trustworthy core of a network. They are designed to work continuously for long periods under heavy workloads to run the network operating system (NOS) and deliver network services.

Servers differ from the average computer in terms of:

Memory - servers require large amounts of RAM to work efficiently. Application servers require huge amounts of RAM to run programs for remote users.

Storage - servers need very large and fast hard disks. Many large servers use RAID ( Redundant Array of Independent [or Inexpensive] Disks) arrays for maximum reliability and speed. RAID uses a group of hard disks that work as a unit and usually offer built-in backup of data. RAID disks are usually "Hot Swap" drives that can be removed and inserted without turning off the server or disrupting the network's operation.

Processing power - while processing power is not so important in a file server, application servers benefit greatly from having multiple CPUs.

Backup - most servers have inbuilt high-capacity tape backup drives to protect against data loss. Tape drives usually use QIC (Quarter Inch Cartridge) tapes.

Connectivity - servers often have two or more fast network cards to multiply the rate at which they can send and receive data to the rest of the network.

Robustness - since servers run all day for years on end, the components used in them need to be of higher quality than those in the average desktop computer. As you may suspect a server will cost far more than a desktop PC - up to ten times as much.

Scalability - servers are designed to be expandable as network demand grows. Scalability is the ability to increase the size and power of equipment and networks as required. Many servers let you add up to 8 hard disks, two power supplies, two NICs, two CPUs etc. Designing and engineering this expandability is expensive.

The larger the network, the more work a server must perform. Bigger networks often use multiple servers to share the workload. Load balancing software can be used to distribute the workload efficiently between the servers.

On smaller networks, most network services are performed by software in a single server. To ease the strain on an overworked server, networks can use specialist servers dedicated to certain jobs. They include:

Login servers - which authenticate users
Proxy servers - which cache downloads
DHCP servers - which allocate IP addresses to users
CD towers and Virtual CD servers - which imitate large CD towers
Web servers and FTP servers - which serve web pages or files
Email servers - which receive, store and distribute email
Print servers - which manage print job queues.

Using server blades can also help out busy servers. These slim units plug easily into a network and act as extra file servers. Network storage can be enhanced just by plugging in NAS (Network Access Storage) units. With up to 960G of hard disk in a slim package, NAS devices greatly expand a network's storage capacity.

worksheets
. history
. why network
. osi model
. connecting
. protocols
. technology
. topologies (tla)
. issues
. network types
. design
. economics
. economics (cs)
- solutions -

quizzes
. why network
. osi model
. connecting
. protocols
. technology
. topology
. issues
. network types
. design
. economics

networking curriculumsupport CD for seniorsecondary studies

networking > technologies > servers

Servers

networking curriculum
support CD for senior
secondary studies