Traditional stand-alone tower servers are feasible and economical for many IT environments, such as small offices, remote locations or those with ample floor space. However, as the number of servers increase, energy consumption, cooling requirements and space utilization become major concerns and can limit growth. Rack-mounted and bladed servers are sound solutions for increasing IT capacity within an already-crowded computing environment. Although they share many similarities, there are essential differences between these types of servers that may make one a better solution for your particular environment.
The following descriptions help to better define each type of server:
Tower servers: These are upright, stand-alone units that contain all traditional server components: hard disks, motherboards and central processing units (CPUs), networking, cabling, power and so on. Tower servers generally require more space than blade or rack-mounted servers, and scalability in such designs is restricted to the available floor and wall space.
Bladed servers: These are small form factor servers designed for high-density footprints. Many components—power, cooling and ventilation, networking and other interconnects—have been removed from the servers themselves and are shared among servers within an enclosure. A blade enclosure can be more economical and scales better than typical tower units.
Rack servers: These are complete servers specially designed for ultra-compact vertical arrangement within a rack skeleton or cabinet. This configuration uses floor space efficiently, offers centralized cable and server management and increases infrastructure scalability.
All three types of servers offer hot-swappable components that you can replace without disruption to other units or their services in a load-balancing arrangement. However, rack servers are generally designed to work as a logical and cohesive whole but without the tight integration found with server blades, which makes rack servers more flexible in some situations. In addition, you can run servers from different manufacturers in the same rack enclosure because the servers don't share proprietary components.