Even old Svätopluk new that three wattles are stronger than one. We can apply his wisdom to IT world through cluster solutions. Cluster is a group of independent servers cooperating on one task execution. It consists of processing nodes, their interconnections and shared disk subsystem.

Clusters share common data but do not share common memory. Each node has its own system memory, own operating system, database instance and application software.

Clusters facilitate simple system performance upgrade. Redundant software and hardware components improve system availability to users and its resistance to failures. These characteristics are common to all cluster systems. Each system differs in its architecture and implementation according to particular needs.