Server clusters are most often used in business where high data availability is the main factor.
- Online gambling and online casinos
- Companies that maintain databases
- Medical industry
- Stock exchange industry
- Finance industry
- Insurance institutions
A server cluster consists of several physical servers, called nodes, that connects with each other to ensure highly available services to customers. Cluster computing consists of resource groups that are made of applications and services, as well as resource group configuration to include all elements for the applications, associated network name and IP address. Each node can have multiple resource groups and resources can have specific dependencies to indicate which one needs to come online or offline during failover. This allows to run collection of resources as a separate server on the network. You can use server clusters for file servers, database servers and messaging servers.
DEAC’s high availability cluster runs on each node and controls server cluster’s operations. There are multiple software components to ensure monitoring, transfer resources from one node to another and maintain consistency of cluster computing.
Each server cluster differs with its components and internal control system. Usual server cluster components are database manager, node manager and failover manager, which work closely together to ensure great performance.
Database manager maintains a local copy of the server cluster configuration database, which contains information about all items in a cluster and it replicates all changes to all nodes in the cluster.
Node manager provides a local list of nodes, networks and network interfaces in the cluster and ensures that all nodes in the cluster have the same list of functional nodes. Node manager also monitors nodes to detect node failure.
Failover manager manages resource dependencies, launches resources and initiates failover of resource groups; as well as determines which resource group should be on each node and if necessary, reassign nodes ownership of the resource group to another.