The Difference between Cluster and Load Balancing

What is the difference between clustering and load balancing? The concepts of clusters and load balancing are often mentioned together. In the server field, what are clusters and load balancing, and what are the correlations and differences?

Cluster concept and characteristics

A cluster is a loosely coupled collection of computing nodes composed of two or more node machines (servers), providing users with a single customer view of network services or applications (including databases, Web services, and file services, etc.) At the same time, it provides fault recovery capabilities close to fault-tolerant machines.

A cluster system is generally interconnected through corresponding hardware and software through two or more node server systems, and each cluster node is an independent server running its own process. These processes can communicate with each other, and to the network client it is like forming a single system, working together to provide users with applications, system resources and data.

In addition to providing services as a single system, the cluster system also has the ability to recover from server-level failures. The cluster system can also increase the processing capacity of the server from the inside by continuing to increase the server in the cluster, and provide inherent reliability and availability through system-level redundancy.

The role of load balancing

The load balancing system enables the load traffic of each node to be equally and reasonably allocated in the server as possible. The load needs to be balanced and calculated by the application to handle port load or network traffic load. Such a system is very suitable for a large number of users running the same set of applications.

Each node can handle a portion of the load, and the load can be dynamically distributed among nodes to achieve balance. The same is true for network traffic. Usually, the web server application receives a large amount of network traffic, which cannot be processed quickly, which requires sending the traffic to other nodes. The load balancing algorithm can also be optimized according to the different available resources of each node or the special environment of the network.

The difference between cluster and load balancing

For example: imagine the computer as an adult, if you want to complete the writing of a document.

1. This document is divided into multiple sub-documents by multiple people, each person completes a part, and finally assembled into a complete document, this is the work of the cluster.

2. If this document is placed on one machine, simultaneous access by multiple people will result in slower response speed. At this time, the network manager puts a few more machines, each machine has this document, and the visitor will be automatically assigned to This document is processed on fewer servers, which is called load balancing.

3. If this document writing work needs to write more than one document, but multiple documents, then multiple people will process part of it separately (and the same person processes the same part each time), this is called distributed .