U. Glaeser

Server Types
Servers are optimized for cost, performance, support, and the usage model. An e-commerce transactionprocessing
server will require fast network interface for quick user response, powerful central processing
unit (CPU) to handle database management, and scalable architecture for possible future enhancements.
An e-commerce server needs to be reliable and secure, without securing issues such as fraud, to ensure good
customer experience. A variety of servers such as proxy, Web cache, data processing, communication,
video, file, and compute are used.
A server needs to be optimized for most frequently used applications and the usage model. Typical
server configurations have several high performance CPUs, large system memory size, and support for
high-speed I/O for storage systems and network interfaces. As an example, a file server is cost-optimized
by using several CPUs, high-speed network interface and extensive storage subsystems. Using more powerful
CPUs than a file server and large amount of system memory are the optimizations used for a compute
server. A compute server may be further optimized to run specific applications such as transaction processing.
Configuration of the hardware elements and software tuning are used to ensure peak performance
and lowest-cost infrastructure.
Server Deployment Considerations
Optimal server deployment requires many requirements. For example, Internet service providers’ (ISP)
servers have extensive communication network capabilities. In this section, some of these issues will be
detailed.
Server Features
A term commonly used to address many of the physical issues in server design is reliability, availability,
and serviceability (RAS). RAS and other elements are:
1. Reliability: Customers expect reliable and robust services continually. Providing Internet services
to customers such as banking and brokerage services requires special consideration. During business
hours, if server goes offline, the revenue loss and potential liability may be significant. The
majority of servers include various forms of reliability detecting and enhancing features. Alternatively,
multiply redundant server configurations can be used to improve reliability of the infrastructure.
Many application and operating system software providers include reliability features
for their server products. Failure prevention solutions include:
• Reducing probability of a failure through additional hardware and software features (some of
the techniques used are independent operating system images on each server node and error
correcting code (ECC) hardware features)
• Minimizing the effect of failures by designing hardware and software robustness features such
as fault isolation and provisioning
• ECC memory scrubbing to detect and correct single bit errors that cause system crash due to
accumulation of soft memory errors
• System management interrupts handlers that allow special software to interface with hardware
error detection and fault isolation independent of the underlying operating system
• High performance and fault tolerant storage architectures such as redundant array of independent
disks (RAID) are used to ensure data and operational integrity.
2. Availability: With the rapid growth of electronic businesses, companies need to ensure that their
systems are running 24 h everyday. Some business server’s downtime costs are in the order of
millions of dollars. Traffic capacities beyond the system capability and component failures are two
of the many sources of system failure. Modern servers are designed to accommodate ever-increasing
traffic and system capacity by using more extensive I/O capability, powerful CPUs, and large system
memory. Online management systems are also used to ensure system resources are not exhausted
or overdriven. Using duplicate resources such as power supplies, CPU, and even multiply redundant
© 2002 by CRC Press LLC