How do blade servers work?

Blade servers offer several ad­vant­ages including a compact and modular design and small footprint because of their high server density. The ultra-thin server blades are housed in compact en­clos­ures, ensuring high server density for optimum capacity, flexible IT ad­min­is­tra­tion and lower energy con­sump­tion.

Blade servers were invented in the 2000s by RLX Tech­no­lo­gies in Houston. The first com­mer­cial blade server was developed in 2001 by Chris­toph­er Hipp, the ‘father of blade tech­no­logy’, and David Kirkeby. As compact, scalable servers with modular design, they met the demands for space-saving, powerful servers for dedicated tasks.

Blade servers are con­sidered one of the most compact server tech­no­lo­gies available due to the server density, reduced cabling and efficient power con­sump­tion. This makes them suitable for optimal pro­cessing and dis­tri­bu­tion of workloads, con­sol­id­a­tion of network and storage devices, and dedicated use for specific, business-critical ap­plic­a­tions. Blade servers offer flexible scaling of computing ca­pa­cit­ies due to their high, modular server density which also makes them suitable for use in spatially limited or large data centres with high energy demands.

The core of a blade server are the chassis and the blades. The chassis is usually an elongated, box-like enclosure that contains the thin blades. Blades are es­sen­tially printed circuit boards func­tion­ing as servers. They usually contain cor­res­pond­ing storage systems, pro­cessors, network con­trol­lers, input/output ports and hot bus adapters.

The structure of a blade server is as follows:

• Chassis: Box-shaped, small enclosure con­tain­ing all elec­tron­ic com­pon­ents including server and racks
• Blades: Carrier units con­tain­ing servers and server com­pon­ents
• Server: Housed in in­di­vidu­al, modular blades and com­pris­ing the servers including com­pon­ents such as pro­cessors, dedicated programs and input/output ports
• Racks: Serve as external racks for blade servers to be grouped and housed as a single unit in a server room
• Backplane: A component of racks through which the modular blade servers can be connected via cabling, power sources or printed circuit boards

Blade servers are used for a diverse range of space- and energy-saving functions. Since blade servers can be reserved for dedicated tasks due to their modular design, they are often used for the dis­tri­bu­tion of workloads or business-critical ap­plic­a­tions.

Common ap­plic­a­tions include:

• Vir­tu­al­isa­tion: Thanks to vir­tu­al­iz­a­tion of apps and hardware, physical IT in­fra­struc­tures can be reduced. Because of the flexible and compact design, blade servers are suitable for software and hardware ab­strac­tion to use IT resources more ef­fi­ciently.
• File sharing: Blade servers perform classic server tasks such as backing up, restoring, and trans­fer­ring files between endpoints and digital nodes.
• Cluster-computing und load balancing: Blade servers often serve as com­pon­ents in cluster computing and server clus­ter­ing to provide high avail­ab­il­ity, scalab­il­ity, load balancing and failover services.
• Web hosting: The modular server units provide flexible scalab­il­ity and high avail­ab­il­ity for web hosting.
• File sharing: For dedicated tasks such as file sharing services, blade servers provide high avail­ab­il­ity and reduced downtime as part of computer clusters.
• Webpage caching: Blade servers can sig­ni­fic­antly reduce wait times and downtime when caching websites.
• SSL en­cryp­tion and malware pro­tec­tion: Dedicated blade servers ensure a secure, encrypted data exchange and protect against malware.
• Streaming: Streaming audio and video requires un­in­ter­rup­ted data exchange and blade servers help to optimise real-time streaming.
• Storage: With more servers dis­trib­uted across less space, blade servers offer plenty of storage while consuming less power.
• Website transcod­ing: For a trouble-free display of website content across different end devices, blade servers are suitable for code con­ver­sion of website elements and mobile SEO.

Blade servers differ depending on the equipment and man­u­fac­turer. Market leaders include well-known names such as Cisco Systems, Su­per­mi­cro, Dell and HPE. The most important dis­tin­guish­ing features in terms of equipment include:

• Per­form­ance of CPU: Pro­cessors and pro­cessing units from man­u­fac­tur­ers such as Intel, Sun Mi­crosys­tems, Advanced Micro Devices and Motorola are often found in blade servers. These in turn determine how powerful the server units are.
• Storage media and working memory: For real-time in­form­a­tion pro­cessing, blade servers depend on suf­fi­cient memory in the form of SSD or HDD and good random access memory (RAM). Blade servers combine different RAM systems, such as static RAM, which stores data in its original state, or dynamic RAM, which allows for on-the-fly updates. For servers that rely on pro­cessing visual data, DDR SDRAM is usually used as dynamic random access memory with doubled data rate.
• Con­nec­tion options: Blade server con­nec­tions can be made via a token ring, an Ethernet output, via fibre optic channels or a fieldbus network protocol.
• Con­nec­tion options to storage systems: Blade servers can be connected to storage using different port types, including FireWire, SATA, SCSI, DAT, FC and iSCSI.

The al­tern­at­ives to blade servers tend to be even more compact. They include brick servers, for example, which do not require a case at all and therefore take up even less space. Other server al­tern­at­ives are cartridge servers that are similar in size to a printer cartridge. These are closely linked to micro servers usually intended for specific purposes and contain modular server cart­ridges.

However, blade servers and their al­tern­at­ives are similar in that they strive to achieve a high and powerful server density via cluster computing while saving as much space and energy as possible. Basically, the server tech­no­lo­gies of the future are becoming ever smaller and more efficient. Modular models offer more ad­vant­ages in terms of main­ten­ance, servicing and scaling compared to static server systems.

In addition to blade servers, rack servers are often used. They are in similar in that they feature a space-saving design for high computing power but differ in some essential aspects. Rack servers are usually mounted ver­tic­ally in struc­tures that resemble shelves. Like blade servers, the number of stacked rack servers can be expanded or reduced. Here, the server per­form­ance adapts to the CPU re­quire­ments, available space and in­di­vidu­al projects. In other words, they are modularly designed and con­fig­ur­able systems, but their design is more static than that of blade servers.

Blade servers tend to be used in projects with high power re­quire­ments and dedicated ap­plic­a­tions. That’s where the dif­fer­ences between blade servers and rack servers become obvious. Blade servers usually consist of servers that are reserved for specific ap­plic­a­tions. The server blades in the chassis are usually stacked ho­ri­zont­ally and used for one dedicated task per blade. In addition, unlike rack servers, in­di­vidu­al blade servers usually do not act as main servers but are active as combined blade server stacks.

A major pro of blade servers over the somewhat larger rack servers is their ease of main­ten­ance and repair. Server blades are easy to replace and main­tained on a modular basis. The con is that companies can be dependent on the com­pon­ents of a par­tic­u­lar man­u­fac­turer and thus suffer from a vendor lock-in. Nev­er­the­less, with blade servers you save on complex cabling and benefit from a space-saving, flexible and efficient server tech­no­logy.