A web server can actually mean one of two different things, either the actual computer hardware, or the software that runs on the web server, receiving requests from clients and responding to them. Here we will take a look at the hardware.
At first glance, the specifications of a web server may be very similar to the type of computer used as a desktop machine by many people, and in fact most desktop machines could be used as a server, given the right software. Like desktop machines, a server will have a CPU, RAM, a hard drive and an Internet connection. However, when you look more closely at these specifications, the differences become apparent. The speed of the CPU is less important in a server, as servers do not have high-end graphics requirements. Nowadays, it is becoming common to see two or more CPUs, rather than one faster CPU. Memory sizes tend to be similar to those of desktop machines, depending on the purpose for which the server is intended. Most servers will have more than one hard drive, which allows for a RAID set-up to be used for data integrity, and the hard drives will also tend to be larger than those used in a typical desktop machine. Servers may also have more than one power supply. Bear in mind that all of these components will normally be built to a higher standard, as reliability is important.
Servers used by web hosting companies are normally housed in racks, where many servers are mounted together. However, the latest trend is for blade servers. These are “stripped-down” computers, consisting of just processors and memory, plus an input/output connection. All of the other components needed by a typical computer, such as power and disk storage, are supplied externally, through the blade enclosure. This results in significant savings in space and cost, since many unnecessary components are not needed.
Servers are kept in a data center. This facility will typically have climate-controlled rooms to house the servers, where the temperature is kept at around 68 – 70 degrees. This helps to keep the servers operating normally, as too much heat can degrade performance, or even cause a shut-down. The data center will also have multiple power supplies, including stand-by generators, to ensure that all systems will still function even if the main power supply fails. There will also be extensive fire detection and prevention devices installed in case of fire.