network clusters

A cluster is a logical grouping of independent servers that work together to run a common set of applications and provide the image of a single system to the client and application. The servers are physically connected by cables and programmatically connected by cluster software. All the servers in a cluster are transparent to a user. Each instance of the server in the cluster is called a Node.

The concept of a cluster involves taking two or more computers and organizing them to work together to provide higher availability, reliability and scalability than can be obtained by using a single system. When failure occurs in a cluster, resources can be redirected and the workload can be redistributed. Typically, the end user experiences a limited failure, and may only have to refresh the browser or reconnect to an application to begin working again.

clusters can be used to solve three typical problems:
Need for High Availability. High availability refers to the ability to provide end user access to a service for a high percentage of scheduled time while attempting to reduce unscheduled outages. A solution is highly available if it meets the organization's scheduled uptime goals. Availability goals are achieved by reducing unplanned downtime and then working to improve total hours of service operation.

Need for High Reliability. High reliability refers to the ability to reduce the frequency of system failure, while attempting to provide fault tolerance in case of failure. A solution is highly reliable if it minimizes the number of single points of failure and reduces the risk that failure of a single component/system will result in the outage of the entire service offering. Reliability goals are achieved using redundant, fault tolerant hardware components, application software and systems.

Need for High Scalability. High scalability refers to the ability to add resources and computers while attempting to improve performance. A solution is highly scalable if it can be scaled up and out. Individual systems in a service offering can be scaled up by adding more resources (for example, CPUs, memory, disks, etc.). The service can be scaled out by adding additional computers.

A well-designed service solution uses redundant systems and components so that the failure of an individual server does not affect the availability of the entire service.

As IT staff architect clustered solutions, they need to look carefully at the cluster organization they plan to use. The goal should be to organize servers according to the way the servers will be used and the applications they will be running. Typically, Web servers, application servers and database servers are all organized differently.

At TS4B we have considerable experience in creating a clustered server environment. Our services include:-

• storage clustering
• farm clustering
• pack clustering
• server clustering
• windows 2003 clustering
• sql clustering
• cluster administration
• cluster planning
• microsoft clustering
• lotus notes clustering
• cluster monitoring
• exchange 2003 clustering
• cpu clustering
• blade clustering
• web server clustering