<P> Large traditional single servers would need to be run for long periods without interruption . Availability would have to be very high, making hardware reliability and durability extremely important . Mission - critical enterprise servers would be very fault tolerant and use specialized hardware with low failure rates in order to maximize uptime . Uninterruptible power supplies might be incorporated to insure against power failure . Servers typically include hardware redundancy such as dual power supplies, RAID disk systems, and ECC memory, along with extensive pre-boot memory testing and verification . Critical components might be hot swappable, allowing technicians to replace them on the running server without shutting it down, and to guard against overheating, servers might have more powerful fans or use water cooling . They will often be able to be configured, powered up and down or rebooted remotely, using out - of - band management, typically based on IPMI . Server casings are usually flat and wide, and designed to be rack - mounted . </P> <P> These types of servers are often housed in dedicated data centers . These will normally have very stable power and Internet and increased security . Noise is also less of a concern, but power consumption and heat output can be a serious issue . Server rooms are equipped with air conditioning devices . </P> <P> A server farm or server cluster is a collection of computer servers maintained by an organization to supply server functionality far beyond the capability of a single device . Modern data centers are now often built of very large clusters of much simpler servers, and there is a collaborative effort, Open Compute Project around this concept . </P> <P> A class of small specialist servers called network appliances are generally at the low end of the scale, often being smaller than common desktop computers . </P>

A large collection of servers is called a(n)