High Availability or HA Clusters are defined as computer clusters that are executed in order to provide services. High Availability is known for its ability to carry out a failover. High Availability is able to provide services to the user in case there is a system crash. The HA Clusters are able to detect the errors in the hardware or software. This then allows the user to still use the system even without having to fix the errors.
High Availability clusters are typically ideal for users who build a large database composed of vital information. It is also useful for computers that are connected in a single network and for storage networks.
Here is the system architecture behind High Availability clusters:
- Restoration Process. High Availability goes through five different phases in order to restore the system and allow it to be used by the user. This is one of the best solutions for sudden power outages and crashes of the system. It is a fault tolerance system that works to be able to serve the client in unplanned errors or failures that can hinder the client from working or accessing the database. The restoration process time depends on the size of the server, the number of servers and the outage minutes. High Availability is also available for Linux systems for Linux clustering.
- High Availability Clusters. Nodes are the parts that build redundancy in a High Availability cluster. Redundancy is needed in order for the high storage system to still work efficiently when there is a sudden crash. High Availability clusters are the ones that are used to monitor the state of the nodes that are found inside the clusters.
- Nodes. The basic size of a high availability cluster is a cluster that is made up of two nodes. There are different models for the nodes. Some of these models are the Active/Active, Active/Passive, N+1, N+M, N-to-1 and N-to-N. Nodes work when there is a power outage or sudden crash. The database will be able to start because of the cluster nodes that are redundant.
- Functions of Nodes. There are different functions for the nodes. These include disk mirroring that replicates the internal disks so that the system will not crash. Another function is the redundant network connections. Redundant network is done so that when the network fails, the network can still be accessed. The Storage Area Network is also replicated or made redundant so that the storage system will still be connected to the network when power fails. The last function of the nodes is the redundancy in electrical power. This enables the entire system to still run after a crash or a power outage.
This is how High Availability works and some of the elements and technology behind High Availability. High Availability clusters are really helpful for companies that have a huge collection of vital information in their database. High Availability can also save you lots of repairing costs for software and hardware when it crashes.