A server farm or server cluster is a collection of computer servers usually maintained by an enterprise to accomplish server needs far beyond the capability of one machine. Often, server farms will have both a primary and a backup server allocated to a single task, so that in the event of the failure of the primary server, a backup server will take over the primary server's function.
Server farms are commonly used for cluster computing. Many modern supercomputers comprise giant server farms of high-speed processors connected by either Gigabit Ethernet or custom interconnects such as Infiniband or Myrinet.
Another common use of server farms is for web hosting, which are sometimes referred to as web farms.
Server farms are increasingly being used instead of or in addition to mainframe computers by large enterprises, although server farms do not as yet reach the same reliability levels as mainframes. Because of the sheer number of computers in large server farms, the failure of individual machines is a commonplace event, and the management of large server farms needs to take this into account, by providing support for redundancy, automatic failover, and rapid reconfiguration of the server cluster.
The performance of the very largest server farms (thousands of processors and up) is typically limited by the performance of the data center's cooling systems and the total electricity cost rather than by the performance of the processors. For this reason, the critical design parameter for such systems tends to be performance per watt, rather than performance per processor.