How to do cluster management in Linux

In high availability (HA) systems, clusters are an integral part. Clustering is a practical solution when a single node cannot provide sufficient availability or performance.

Linux is a very popular cluster environment, which provides cluster implementation and support through a variety of ways. In this article, we will learn how to do cluster management in Linux.

1. Cluster management software

Linux uses a number of cluster management software to help administrators easily manage cluster instances of multiple servers. There are many tools to choose from, the most popular of which include Pacemaker, Corosync, and HaProxy.

• Pacemaker is a commonly used cluster management software that can balance load and provide failover functions among multiple servers. It runs on Linux and Unix operating systems and can be used with various services such as Apache, MySQL, PostgreSQL, and NFS.
• Corosync is a tool that collects and distributes cluster configuration data and acts as a backend for Pacemaker. Corosync can set and manage network addresses and service names, and maintain synchronization and communication between nodes.
• HaProxy is a high-performance load balancing software that can be used to manage hundreds or thousands of virtual servers. It balances load across multiple nodes and provides failover capabilities to ensure the system is always available.

2. Configuration file

Cluster management uses configuration files to determine node, storage and load balancer settings. A simplified configuration can be seen in the following example, which is used to create a Pacemaker cluster.

node node1
node node2

primitive apache ocf:heartbeat:apache 
        configfile="/etc/apache2/apache2.conf" 
    op monitor interval="30s"

primitive ip_apache ocf:heartbeat:IPaddr2 
        params ip=192.168.0.100 cidr_netmask=24 
    op monitor interval="15s"

group apache_group apache ip_apache
location apache_location apache_group 
    rule score="50" attribute="hostname" eq=node1

location apache_location apache_group 
    rule score="100" attribute="clusterIP" ne="192.168.0.100"

order start_apache inf: apache ip_apache

Configuration files include node definitions, storage device information and service configurations. It also specifies the roles of different nodes such as primary or standby, failover, load balancer, etc.

3. Security Configuration

In a Linux cluster, security is crucial. It involves aspects such as network security, authentication and access control. Some best practices in security configuration include

• Disable SSH access for the root account
• Set up a firewall to block unauthorized network access
• Configure a service account for the cluster , and restrict their access
• Encrypt disks, messages, and remote access
• Update software and regularly check system vulnerabilities
• Write and execute emergency plans to respond to network attacks and crashes

4. Monitoring cluster

Monitoring is the key to ensuring the normal operation of the system. Linux clusters use different monitoring tools to assess system health, including Nagios, Zabbix, and Cacti.

• Nagios is an open source network monitoring tool that can check the status of multiple services such as HTTP, FTP, SSH and smtp and provide alerts.
• Zabbix is ​​an enterprise-level monitoring tool with a distributed architecture and flexible notification mechanism, including SMS, Email and Web messages.
• Cacti is a graphical tool for monitoring network and system resources. It provides various plugins and reports that can be used to evaluate cluster performance and help identify bottlenecks and failures.

After implementing the cluster, administrators need to monitor the system and cluster regularly. Additionally, they should handle system errors when necessary and maintain the stability and reliability of the cluster.

Summary

Cluster management in Linux requires an in-depth understanding of different tools and configurations. Only in this way can administrators effectively formulate cluster strategies and monitor cluster status. Best practice is to employ multiple monitoring and management tools and regularly update and update your systems to ensure data security and availability.

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