A blade server is a server chassis housing multiple thin, modular electronic circuit boards, known as server blades. Each blade is a server in its own right, often dedicated to a single application. The blades are literally servers on a card, containing processors, memory, integrated network controllers, an optional Fiber Channel host bus adaptor (HBA) and other input/output (IO) ports.
Blade servers allow more processing power in less rack space, simplifying cabling and reducing power consumption. According to a SearchWinSystems.com article on server technology, enterprises moving to blade servers can experience as much as an 85% reduction in cabling for blade installations over conventional 1U or tower servers. With so much less cabling, IT administrators can spend less time managing the infrastructure and more time ensuring high availability.
Each blade typically comes with one or two local ATA or SCSI drives. For additional storage, blade servers can connect to a storage pool facilitated by a network-attached storage (NAS), Fiber Channel, or iSCSI storage-area network (SAN). The advantage of blade servers comes not only from the consolidation benefits of housing several servers in a single chassis, but also from the consolidation of associated resources (like storage and networking equipment) into a smaller architecture that can be managed through a single interface.
A blade server is sometimes referred to as a high-density server and is typically used in a clustering of servers that are dedicated to a single task, such as:
- File sharing
- Web page serving and caching
- SSL encrypting of Web communication
- The transcoding of Web page content for smaller displays
- Streaming audio and video content