Asymmetric and Symmetric Clustering System

Clustering systems are similar to parallel systems as they both have multiple CPUs. However, a major difference is that clustered systems are created by two or more individual computer systems merged together. The primary goal is to provide high availability and fault tolerance by distributing workload across multiple nodes. There are two main types of clustering systems: asymmetric and symmetric clustering systems.

Asymmetric Clustering System

In an asymmetric clustering system, one node acts as the primary server that runs all applications, while one or more nodes remain in hot standby mode. The standby nodes continuously monitor the primary server and are ready to take over immediately if the primary node fails. This creates a master-slave relationship where only one node is actively processing at any given time.

How Asymmetric Clustering Works

• The primary node handles all incoming requests and runs applications while standby nodes remain idle but ready.

• Heartbeat monitoring occurs where standby nodes continuously check the health of the primary node.

• When the primary node fails, a standby node immediately takes over and becomes the new primary.

• All nodes share access to common storage to ensure data consistency during failover.

Symmetric Clustering System

In a symmetric clustering system, all nodes actively run applications and simultaneously monitor each other. This approach is more efficient than asymmetric clustering as it utilizes all available hardware resources instead of keeping nodes idle in standby mode. Each node can process requests independently while providing mutual monitoring for fault tolerance.

Comparison

Advantages

Asymmetric Clustering

• Simple management − Clear master-slave hierarchy makes administration easier.

• Fast failover − Standby nodes can take over immediately without complex coordination.

• Predictable performance − Single active node ensures consistent response