What is ha in linux

In Linux, the full name of HA is "High Availability", which means "high availability" in Chinese and can be used to represent a high-availability cluster; a high-availability cluster can automatically transfer resources and resources when a single node fails. The service is switched to ensure that the service is always online, thereby reducing losses caused by the error-proneness of computer hardware and software.

#The operating environment of this tutorial: linux7.3 system, Dell G3 computer.

What is ha

High Availability Cluster in Linux? The original English text is High Availability Cluster, referred to as HACluster. Simply put, a cluster is a group of computers that serve as a whole to users. Provides a set of network resources. These individual computer systems are the nodes of the cluster.

The emergence of high-availability clusters is to make the overall service of the cluster as available as possible, thereby reducing losses caused by the error-proneness of computer hardware and software. If a node fails, its backup node will take over its responsibilities within a few seconds. Therefore, the cluster never goes down for users.

The main function of high-availability cluster software is to automate fault checking and business switching. A high-availability cluster with only two nodes is also called dual-machine hot backup, which uses two servers to back up each other. When one server fails, another server can assume the service task, thus automatically ensuring that the system can continue to provide external services without manual intervention. Dual-machine hot standby is only a type of high-availability cluster. High-availability cluster systems can support more than two nodes, provide more and more advanced functions than dual-machine hot standby, and can better meet the changing needs of users.

A high-availability cluster means that when a node or server fails, another node can automatically and immediately provide services to the outside world, that is, transfer the resources on the failed node to another node, so that the other node With resources, services can be provided externally. High-availability clusters are used to automatically switch resources and services when a single node fails, thus ensuring that services are always online. This process is transparent to the client.

The measurement standard of high availability cluster

HA (High Available), high availability cluster is based on the reliability and maintainability of the system. Metric. In engineering, mean time to failure (MTTF) is usually used to measure system reliability, and mean time to repair (MTTR) is used to measure system maintainability. So availability is defined as: HA=MTTF/(MTTF MTTR)*100%

Specific HA measurement standard:

99% Downtime does not exceed 4 days a year

99.9% Downtime does not exceed 10 hours per year

99.99% Downtime does not exceed 1 hour per year

99.999% Downtime does not exceed 6 minutes per year

Related recommendations: "Linux Video Tutorial"

The above is the detailed content of What is ha in linux. For more information, please follow other related articles on the PHP Chinese website!