Knowing a few specifics about server hardware will help tie server specifications to system needs when buying a server or building one from components.
Standard Server Build Structure
The basic component structure of a server is similar to that of a PC. Since most servers are meant for 24/7 operation; and servers for virtualization have powerful, multi-core processors and expansive disk space to handle a heavier computing load and data storage, server components are more robust.
Server Motherboards
Servers for virtualization have motherboards with LGA 2011-3 sockets that support larger CPUs with the X99 chipset (Intel Xeon E5 and Intel Core i7 X-series processors, for example) that have multiple cores and threads for running virtual machines. AMD server CPUs have their own socket types and are not compatible with Intel. Some motherboards have dual CPU sockets to add processor redundancy for 24/7 uptime.
When you talk about scalability in servers, one huge consideration is the number slots in the motherboard. The more slots there are, the more room there is for expansion. Different types of slots include DIMM slots for RAM, and PCI-e slots for graphics cards and next-generation solid-state storage drives.
Server Memory
Many servers use Error Correcting Code memory, or ECC DRAM, that adds tolerance for data corruption. ECC DRAM is not compatible with motherboard DIMM slots used for standard DDR4 PC memory.
Server Processors
The number of cores and threads dictates performance for server CPUs. Clock speed, measured in GHz, plays a role in how fast the processor executes instructions, but in terms of functionality for modern servers, frequency does not gauge performance as much. A larger amount of cache memory boosts performance: the cache stores frequently accessed data for faster recall, which speeds up server performance in many situations.
Budget-level dedicated servers and NAS typically have a low-power dual- or quad-core processor (Intel Core i3) typically found in PCs; more expensive servers have CPUs capable of greater processing power are more common in large tower servers and rack models.
Server Networking
Every server is meant for network use. Bandwidth considerations are important; inadequate networking components will sap performance for the system. For virtualized servers, a dual-port or quad-port network interface card (NIC) is recommended for greater connectivity, and a 10 gigabit (Gbe) NIC boosts performance for environments with an increased number of end users.
Server Storage
File servers—sometimes called storage servers or Network Attached Storage (NAS) —have room for multiple hard drives that protect against data loss in the event of drive failure, a configuration called a RAID array. They are meant to make available data for a pool of end users. A group of file servers configured together in as Storage Area Network (SAN) improves data availability across larger networks, and can improve application performance over multiple satellite office networks.
Enterprise hard drives have built in fault tolerance and a faster interface (SAS) than those in consumer drives (SATA) SAS drives have a premium price point. Make sure to note compatibility when you buy storage drives, as SATA and SAS drives are not interchangeable. Other interfaces for server storage include USB 3.0 for external drive connections, and Thunderbolt, the high-speed Apple interface.
Server Form Factors
Server cases have different form factors. A MicroServer is a square-ish server box, typically used as a file server or NAS, or a low-power single use server. It supports basic RAID and usually has a low power server processor, ideal for a small home office. Tower systems resemble full-size desktop PCs and vary in computing power and specifications; low-end models offer good value and are easily expandable—ideal for back office and retail settings.
Medium and large companies usually store IT infrastructure in server racks. Rack servers have chasses designed for stacking vertically in server racks. Size measurements for standard rack servers are designated by units starting at 1U, which has a width of 19 inches and 1.75 inches in height. Servers range from 1U-4U. The standard height for a server enclosure is 42U tall.
Server Software
Server software manages user access to different parts of the data infrastructure using credentials or authentication information, and makes available data (content) beyond the physical LAN. Windows Server is the most commonly known administration system among IT professionals, which makes support relatively easy to procure. The value proposition to buy Windows Server licensing hinges on readily available support technicians.
Linux systems, which are popular especially for larger businesses, are managed with open source software that is free of licensing costs. The tradeoff is that Linux systems have more custom-built features, which places a higher demand on specialized administration staff that can command a higher fee for support services.