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This article introduces the relevant knowledge of "the concept of cluster and load balancing and how to build a cluster with apache and tomcat". Many people will encounter this dilemma in the operation of actual cases, so let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

I. the concept of cluster and load balancing

(1) the concept of cluster

Cluster is a loosely coupled set of computing nodes composed of two or more node computers (servers), which provides users with a single customer view of network services or applications (including database, Web services, file services, etc.), while providing fault resilience close to fault-tolerant machines. Cluster systems are generally interconnected by two or more node server systems through the corresponding hardware and software, and each cluster node is an independent server running its own process. These processes can communicate with each other, forming a single system for network clients, 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. Cluster systems can also increase the processing capacity of servers internally by continuing to add servers in the cluster, and provide inherent reliability and availability through system-level redundancy.

(2) Classification of clusters

1. High performance Computing Science Cluster:

An IA cluster system that aims at solving complex scientific computing problems with jie. It is the foundation of parallel computing. Instead of using a special parallel supercomputer consisting of ten to tens of thousands of independent processors, it uses a set of IA servers of CPU in 1-2-4 linked through high-speed connections, and communicates on the common messaging layer to run parallel applications. This kind of computing cluster has the same processing power as the real super parallel machine, and has excellent performance-to-price ratio.

2. Load balancer cluster:

Load balancing cluster provides a more practical system for the needs of enterprises. The system enables the load and traffic of each node to be distributed as evenly and reasonably as possible in the server cluster. This load requires balanced computing applications to handle port load or network traffic load. Such a system is ideal for a large number of users running the same set of applications. Each node can handle part of the load, and the load can be dynamically distributed among the nodes to achieve balance. The same is true for network traffic. Usually, the network server application receives a large amount of incoming traffic and cannot process it quickly, so it needs to send the traffic to other nodes. Load balancing algorithm can also be optimized according to the different available resources of each node or the special environment of the network.

3. High availability cluster:

In order to ensure the high availability of the overall services of the cluster, the fault tolerance of computing hardware and software is considered. If a node in a high-availability cluster fails, it will be replaced by another node. The whole system environment is consistent for users.

In practical cluster systems, these three basic types are often mixed and mixed.

(3) typical clusters

Scientific computing cluster:

1 、 Beowulf

When it comes to Linux clusters, many people's first reaction is Beowulf. That is the most famous Linux science software cluster system. In fact, it is a generic term for a set of public software packages that run on the Linux kernel. These include popular software messaging API, such as "messaging interface" (MPI) or "parallel virtual machine" (PVM), modifications to the Linux kernel to allow the combination of several Ethernet interfaces, http://www.bbqmw.net/ high-performance network drivers, changes to the virtual memory manager, and distributed interprocess communication (DIPC) services. The public global process identification space allows access to any process from any node using the DIPC mechanism.

2 、 MOSIX

Beowulf is similar to a cluster-supporting plug-in software installed for the system, providing application-level clustering capabilities. MOSIX completely modifies the kernel of Linux and provides clustering capability from the system level. It is completely transparent to the application. The original application program can run normally on the MOSIX system without modification. Any node in the cluster is free to join and remove to take over the work of other nodes or to expand the system. MOSIX uses adaptive process load balancing and memory booting algorithms to maximize overall performance. Application processes can be migrated between nodes to take advantage of the best resources, similar to symmetrical multiprocessor systems that can switch applications between processors. Because MOSIX implements the cluster function by modifying the kernel, there is a compatibility problem, and some system-level applications will not work properly.

This is the end of the introduction to "the concept of cluster and load balancing and how to build a cluster with apache and tomcat". Thank you for reading. If you want to know more about the industry, you can follow the website, the editor will output more high-quality practical articles for you!

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