A blade server is essentially a housing for a number of individual minimally-packaged computer motherboard "blades", each including one or more processors, memory, storage, and network connections, but sharing the common power-supply and air-cooling resources of the chassis. The idea behind blade servers is that by placing many blades in a single (typically rack-mounted) housing, sytems can be created which are more compact and powerful, but less expensive than traditional sytems based on mainframes, or server farms of individual computers.

Blade servers are ideal for specific purposes such as web hosting and cluster computing. Individual blades are typically hot-swappable. One of the greatest advantages of blade servers is that they allow the use of a single reliable heavy-duty DC power supply, rather than many small and unreliable power supplies. In addition, because blade servers use custom-designed blade boards rather than commodity PC motherboards, they can be designed to have significantly more efficient air-cooling airflow than a rack of servers.

Blade servers increasingly allow the inclusion of functions such as network switches and routers as individual blades.

Although blade server technology in theory allows for open, cross-vendor solutions, at this stage of development of the technology, users experience fewer problems when keeping with blades, racks and blade management tools from the same vendor. Eventual standardisation of the technology will hopefully result in more choices for consumers; increasing numbers of third-party software vendors are now entering this growing field.

Blade servers are not, however, the answer to every computing problem. They may best be viewed as a form of productized server farm that borrows from mainframe packaging, cooling, and power supply technology. For large problems, server farms of blade servers are still necessary, and because of blade servers' high power density, can suffer even more acutely from the HVAC problems that affect large conventional server farms.

In the long run, the architecture of blade servers is expected to move closer to mainframe architectures, in particular in terms of resource virtualization and higher levels of integration with the operating system to increase reliability.

See also

• Server farm
• Grid computing