System uptime is obviously a prerequisite to speed and performance. Several technologies can improve overall fault-tolerance, the simplest being spot solutions such as using a RAID array instead of a single disk drive, which is standard operating practice for most organizations today. Load distribution and load balancing are two other popular options for enhancing server reliability. Load-distribution technologies such as the round-robin DNS (Domain Name Service) protocol redirect traffic to the next host in the target list, without knowing the host's load or even checking if the host is up and running. This approach helps lighten the burden on individual systems, but it doesn't do anything to guarantee system availability.
Load balancing, meanwhile, relies on active performance monitors to measure the load of each server and then redirect queries to the host with the least load. This is important if you have a mix of slow and fast computers and want to distribute the load according to capability, or if you want to avoid directing traffic to a failed system.
Operating systems, meanwhile, are beginning to incorporate native clustering solutions. These technologies essentially mimic the load-distribution model, with enhancements to the native operating system, rather than relying on external systems. Windows 2000 and later versions come with clustering, as does the latest Linux kernel, for instance. Although native clustering provides redundancy and fault-tolerance, one potential trade-off is that it's typically designed for servers running physically close together. That can sometimes make deployment across WANs impractical or impossible. If you don't need carbon copies of each system, these clusters are probably overkill and load balancing is a better option.
Be Prepared
Ensuring that your applications, servers and network perform optimally depends primarily on how well you stay on top of your resources. That entails performing a comprehensive audit of your existing systems that takes into consideration future use. After your performance analysis and subsequent buildout come the comprehensive testing and management of the system. Performance planning, including getting to know the underlying technology and business your applications support, can help you avoid major system failures and outages. It pays to be prepared.
