A converged server cluster, or shared storage cluster, integrates multiple discrete hardware components into a single close infrastructure to create a versatile, high availability computing and storage framework. Application usage is virtualised, with shared (and usually replicated) storage.
Components making up a typical shared storage cluster comprise:
Compute and storage nodes are located in separate physical tiers interconnected by switching gear. The separation of compute and storage allows for flexible scaling to boost performance, increase storage or multiple redundancy as usage and policy demand.
The simplest shared storage cluster would be made up of 2 failover compute nodes acting as hypervisors running sets of virtual servers, connected to a single shared storage node. More typically, there would be 2 or more replicated storage nodes so that data is also highly available in case of node failure.