Editing Blade server (section)

== Blade enclosure ==
The enclosure (or chassis) performs many of the non-core computing services found in most computers. Non-blade systems typically use bulky, hot and space-inefficient components, and may duplicate these across many computers that may or may not perform at capacity. By locating these services in one place and sharing them among the blade computers, the overall utilization becomes higher. The specifics of which services are provided varies by vendor.

[[Image:enclosure proliant.jpg|thumb|269px|[[Hewlett-Packard|HP]] BladeSystem c7000 enclosure (populated with 16 blades), with two 3U UPS units below]]

=== Power ===
Computers operate over a range of DC voltages, but utilities deliver power as [[Alternating current|AC]], and at higher voltages than required within computers. Converting this current requires one or more [[power supply unit]]s (or PSUs). To ensure that the failure of one power source does not affect the operation of the computer, even entry-level servers often have redundant power supplies, again adding to the bulk and heat output of the design.

The blade enclosure's power supply provides a single power source for all blades within the enclosure. This single power source may come as a power supply in the enclosure or as a dedicated separate PSU supplying DC to multiple enclosures.<ref name=hpblade>{{Cite web |url=http://h18004.www1.hp.com/products/quickspecs/12330_div/12330_div.html |title=HP BladeSystem p-Class Infrastructure |access-date=2006-06-09 |archive-url=https://web.archive.org/web/20060518152828/http://h18004.www1.hp.com/products/quickspecs/12330_div/12330_div.html |archive-date=2006-05-18 |url-status=dead }}</ref><ref name=sunblade>
[http://www.sun.com/blades Sun Blade Modular System]</ref> This setup reduces the number of PSUs required to provide a resilient power supply.

The popularity of blade servers, and their own appetite for power, has led to an increase in the number of rack-mountable [[uninterruptible power supply]] (or UPS) units, including units targeted specifically towards blade servers (such as the [[Eaton BladeUPS|BladeUPS]]).

=== Cooling ===
During operation, electrical and mechanical components produce heat, which a system must dissipate to ensure the proper functioning of its components. Most blade enclosures, like most computing systems, remove heat by using [[computer fan|fan]]s.

A frequently underestimated problem when designing high-performance computer systems involves the conflict between the amount of heat a system generates and the ability of its fans to remove the heat. The blade's shared power and cooling means that it does not generate as much heat as traditional servers. {{as of | 2009 | alt = Newer}} blade-enclosures feature variable-speed fans and control logic, or even [[Liquid cooling for computers|liquid cooling system]]s<ref name=sunpowerandcooling>[http://www.sun.com/servers/blades/6000chassis/Blade6000_PowerCooling_WP.pdf Sun Power and Cooling]
</ref><ref name=hpthermal>{{Cite web |url=http://h71028.www7.hp.com/ERC/downloads/4AA0-5820ENW.pdf |title=HP Thermal Logic technology |access-date=2007-04-18 |archive-date=2007-01-23 |archive-url=https://web.archive.org/web/20070123051510/http://h71028.www7.hp.com/ERC/downloads/4AA0-5820ENW.pdf |url-status=dead }}</ref> that adjust to meet the system's cooling requirements.

At the same time, the increased density of blade-server configurations can still result in higher overall demands for cooling with racks populated at over 50% full. This is especially true with early-generation blades. In absolute terms, a fully populated rack of blade servers is likely to require more cooling capacity than a fully populated rack of standard 1U servers. This is because one can fit up to 128 blade servers in the same rack that will only hold 42 1U rack-mount servers.<ref name=density>{{Cite web |url=http://h18004.www1.hp.com/products/servers/proliant-bl/c-class/2x220c-g5/index.html |title=HP BL2x220c |access-date=2008-08-21 |archive-url=https://web.archive.org/web/20080829183852/http://h18004.www1.hp.com/products/servers/proliant-bl/c-class/2x220c-g5/index.html |archive-date=2008-08-29 |url-status=dead }}</ref>

=== Networking ===

Blade servers generally include integrated or optional [[network interface controller]]s for [[Ethernet]] or [[host adapter]]s for [[Fibre Channel]] storage systems or [[converged network adapter]] to combine storage and data via one [[Fibre Channel over Ethernet]] interface. In many blades, at least one interface is embedded on the motherboard and extra interfaces can be added using [[mezzanine card]]s.

A blade enclosure can provide individual external ports to which each network interface on a blade will connect. Alternatively, a blade enclosure can aggregate network interfaces into interconnect devices (such as switches) built into the blade enclosure or in [[Blade server#Other blades|networking blades]].<ref name=sunindependentio>[http://www.sun.com/servers/blades/iomodules/ Sun Independent I/O ]</ref><ref name=hpvirtual>[https://www.hpe.com/emea_europe/en/integrated-systems/virtual-connect.html HP Virtual Connect]</ref>