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rack mounted

Built into a cabinet that has a standard width of 19" or 24". All types of electronics and computing devices come in rack-mounted packages, including servers, test instruments, telecommunications components, tape drives and audio and video equipment. The units are bolted to the side frames. If equipment is not rack mountable, it can be placed on shelves. The height of a rack-mounted device is specified in a unit (U) measure or rack unit (RU). 1U (or 1RU) is 1.75" from top to bottom. See blade server.




Rack Mount Cabinet
This is a sales brochure picture showing the variety of shelves available for 19" rack mount cabinets. Side and rear panels, doors, locks, fans and a host of other accessories are also offered. (Image courtesy of AMCO Engineering Company.)






One, Two and Three Rack Units
Each rack unit (U) is 1.75" thick from top to bottom.






A Rack of Betacams
In datacenters and professional studios around the world, equipment is routinely rack mounted. These Betacam videotape recorders are in a TV studio with rooms full of equipment. Each Betacam recorder takes 5U of vertical rack space.






blade server

A server architecture that houses multiple server modules ("blades") in a single chassis. It is widely used in datacenters to save space and improve system management. Either self-standing or rack mounted, the chassis provides the power supply, and each blade has its own CPU, RAM and storage. Redundant power supplies may be an option. Blade servers generally provide their own management systems and may include a network or storage switch. Contrast with blade PC.

Diskless Blades
With enterprise-class blade servers, storage may be external, and the blades are diskless. This approach allows for more efficient failover because applications are not tied to specific hardware and a particular instance of the operating system. The blades are anonymous and interchangeable. In a hyperconverged datacenter architecture, the blade servers each have local storage (see hyperconverged infrastructure). See blade and processor area network.



Disk-Based Blades
Blade servers are widely used in datacenters to save space and ease systems management. This earlier ProLiant unit from HP has redundant power supplies and holds 20 blades in 3U of rack space. The exposed blade on the left is a complete server with hard disk. (Image courtesy of Hewlett-Packard Company.)







Enterprise-Class Blade Server
The BladeFrame from Egenera supports up to 24 blades, each with four Xeon processors. The entire system is managed with Egenera's PAN Manager software via a Web browser. In this picture, one blade is being replaced. (Image courtesy of Egenera, Inc., www.egenera.com)






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