Rack Servers

What are Rack Servers?

A server is a high powered computer designed to store, retrieve and send computer files and data. It processes requests from client computers or programs and delivers the data via the internet or local network. Rack servers, or rack-mounted servers, are servers that are designed to be installed in a low-profile enclosure (rack) designed to hold IT equipment.

These racks contain multiple vertical bays where the servers are installed, minimizing the need for floor space and simplifying supplying power; however cooling the confined space where the servers are crowded is a necessity. When a server is mounted in a rack, it is usually done so with a rail kit that allows the server to slide in and out of the rack to provide easy in-rack serviceability.

What is a Rack Unit?

A rack unit, designated as “U”, is a unit of measurement for standardizing rack servers, racks, and other rack-mounted IT equipment. A rack unit equals 1.75 inches or 44.45 mm. Standard rack heights are designated as 1U, 2U, 3U, and 4U (equal to 1.75”, 3.5”, 5.25”, and 7”). A 2U rack server will, therefore, have a height of 2.5 inches. There are three available widths of rack servers (19”, 23”, and 24”) but 19 inches wide is the most common.

Server Memory

Without delving too deeply into the mechanics of memory, installed server memory is usually SRAM, DRAM, or ECC. Static random access memory (SRAM) is the fastest and the RAM speed is expressed as DDR1, DDR2, etc. SRAM is usually not user replaceable. Dynamic access memory (DRAM) is less expensive but slightly slower than SRAM. It is also replaceable by the user. ECC stands for error-correcting code and has a self checking software that identifies and corrects any errors that might creep into volatile memory. ECC is a type of DRAM that user replaceable but must be compatible with other computer hardware.

Rack Servers Features & Capabilities

• Hot swapping - The capability to replace or add components without shutting down the system
• The ability to update software without a restart or reboot
• Advanced backup capability for frequent backup of critical data
• Redundant power supplies
• Advanced networking performance
• Automatic (invisible to the user) data transfer between devices.
• High security for resources, data and memory protection
• Powerful cooling fans or water cooling systems
• Advanced self-monitoring, such as overheating and disk failure
• Various Connectivity capabilities: USB, video, serial cable
• Number of processor cores - multiple cores speed up processing times and capabilities

Pricing Information

The prices for rack servers vary greatly. The biggest specs that impact price include server speed, memory, storage capability, and integrated security features. Low end rack servers start around $1,000 and range to more than $70,000 for very high end enterprise level servers.