A server cluster is a group of distributed systems controlled by a single IP address. This approach improves availability and allows proper load balancing and scalability of servers.
From a technical point of view each server in the cluster is a separate node with an individual hard disk, temporary memory, and computing resources. For instance, in a cluster with two nodes, if one server fails, the second immediately takes over. This technology known as fault-tolerant clustering, significantly reduces the risk of downtime.
It is best to use several software nodes and web nodes simultaneously as it guarantees hardware redundancy. Such architectures are more commonly referred to as high availability clusters and they are designed to prevent downtime in the event of failures. The effectiveness of a cluster becomes evident when an operating system, which lacks redundancy in a single server, fails. In such a case, your server clients might not even be aware of the failure because there would be no site outages.
How Does Server Clustering Work?
Each cluster comprises several individual servers interconnected by fast transmission lines and software. The outcome is a coherent system capable of handling complex computations. Each server in the cluster is allocated a specific task from a list of common processes.
Why Are Server Clusters Deployed?
Most often, enterprises implement clustered server systems to reduce downtime and to ensure uninterrupted system availability during critical situations. In addition, organizations facing performance degradation employ cluster technology.This allows the separation of computational tasks and database management, ensuring continuous operation for global work tasks.
What Are the Types of Server Clusters?
All server clusters can be divided into 4 categories. Each of them has its unique features and is suited for particular tasks and enterprise capabilities. Let's delve into each of them.
High Availability (HA) Server Clusters
It will be the best solution for high-traffic sites. Thus high availability clusters are commonly used for online stores, as well as for software that requires critical processes to run continuously. These clusters mitigate single points of failure by utilizing redundant hardware and software. High availability clusters consist of a few hosts that assume control of all processes in case of server failures.
Load Balancing Clusters
Such clusters are considered server farms that distribute user requests to different functioning nodes. The primary features of load balancing clusters include faster operation speed, redundancy provision and improved load balancing during workload execution. It is load balancing that allows workloads and functions to be distributed across multiple systems. Simply put, this configuration maximizes resource utilization.
High-Performance and Clustered Storage
Supercomputers or high-performance clusters stand out for their high efficiency, security and capacity. Such systems are typically installed in large enterprises that are characterized by demanding workloads. Such a cluster consists of any configuration systems connected to a single network. These clusters can be linked to storage centers, significantly accelerating task execution.
Clustered storage incorporates at least two storage servers. This type of clustering is designed to boost the efficiency of the overall system, as well as substantially enhance the amount of I/O and security. There are two types of clustered storage architectures: loosely coupled and tightly coupled, each targeting specific processes. For example, the tightly coupled architecture is more focused on the primary storage of information, dividing it into small blocks across different nodes. The loosely coupled architecture is characterized by its flexibility, but it doesn't store data in nodes.
Benefits of Server Clustering
Managing technological failures, websites and software is much more straightforward with clusters. In simple words, a clustered environment ensures your product is consistently accessible on the network, mitigating risks associated with unexpected downtime and system breakdowns.
Flexibility and Scalability
While individual servers can handle a wide range of processes, creating a multi-server architecture with a focus on clustering significantly enhances the scalability and flexibility of your server. In simple terms, clustering allows a single server to scale and meet growing resource demands.
Improved Availability and Performance
Clusters are highly efficient, providing another compelling reason to invest in this solution. While primarily offering hardware redundancy and continuous operation, such systems can also enhance performance. Clusters with a dedicated database server are suitable for accelerating websites and software. This configuration increases efficiency by increasing communication between simultaneous connections.
Reduced IT Costs
Companies need a cohesive architecture for their servers to function as a unified system. At the same time, organizations require networks with pre-defined redundancy to maintain constant service availability. In fact, clustering addresses these issues by reducing the likelihood of downtime, leading to significant cost savings and increased revenue.
Contrary to a common misconception, cluster solutions are not exclusive to large organizations. In fact, this infrastructure is highly configurable, making clusters suitable for companies of any size. In many cases, it provides a highly effective method for workflow optimization.
Basic Components of High Availability Clusters
Much of the effectiveness of a high availability cluster lies in its components. Let's examine the key elements that make up this system.
Nodes are individual servers that constitute the core of a high-availability cluster. Virtual and physical servers that perform the necessary tasks and host the required software are used for this purpose. Such nodes are combined and work together to provide a high level of redundancy and load balance in case of failure of any node.
The efficiency of a high-availability cluster largely hinges on the speed and reliability of the network. In this case, the network forms the backbone of the cluster, ensuring that nodes can communicate with each other and distribute computing resources among themselves.
An important cluster component that aims to evenly distribute traffic among all nodes. This component accepts incoming requests and redirects them evenly across the available nodes, thereby mitigating the risk of overloading individual nodes.
This part is fully responsible for monitoring the status of the nodes within the cluster and managing the failover process during critical situations. Cluster managers employ numerous node monitoring techniques, such as health checking and pulsing.
Storage plays an essential role in a high availability cluster because it enables all nodes to access the required information from a common location. This shared storage ensures that even when certain nodes fail, the remaining ones can still function, supported by the collective resources of the cluster.