What are Clustering Capabilities of Servers?

Before delving into server clustering and its capabilities, let us briefly touch upon the role that a server plays. A server refers to any hardware device or software that accepts and responds to requests that are made over a network by a client device. The client device generates requests for the server and subsequently receives the response of the server. In this way, servers, whether these are hardware-based or software-based, offer functionality to client devices and/or programs through the client-server model. These functionalities are referred to as services. Database servers, mail servers, print servers, proxy servers, application servers, file servers, game servers, web servers etc. are some of the main types of servers.

If we take the example of a web server, which is a type of a server, its function is to accept and fulfill clients’ requests for content of websites (images, HTML pages, videos etc.). A browser or a mobile application is usually a web server’s client and the request is made in the form of a HTTP (Hypertext Transfer Protocol) message. The web server’s response to the request also takes the form of a HTTP message. These web servers are provided by web hosting companies through the service of web hosting. The most renowned web hosting companies are referred to as the “Best Website Hosting Company”, the “Best Cloud Hosting Company”, the “Best Windows Hosting Company” etc.

Equipped with the understanding of what a server is and does, let us proceed to our topic of server clustering. When a group of servers work collectively to deliver high availability to the users, it is referred to as server clustering. A single IP address is used to distribute and manage this unified collection of servers, which is known as a server cluster. A server cluster functions as a single entity and provides high availability, scalability and load balancing. In it, each server is a node and has its own memory (RAM), processing capabilities (CPU) and storage (hard drive). In it, if one server crashes, another takes over immediately. Hence, this type of architecture is referred to as a high-availability cluster. It aids in reducing downtime, when there is component failure, especially for OS (Operating system) failure, which has no redundancy in a single-standing server. In server clustering, hardware redundancy is ensured by utilizing multiple web nodes and app nodes.

There are usually two types of server clusters. One of these is automatic and the other is manual. In automatic clusters, an automatic switchover happens, which is caused by previously configured software. Manual clusters involve a node’s manual configuration and result in downtime, which can be critical for businesses. Hence, a manual cluster isn’t an ideal solution.

Applications that frequently update data usually use clustered servers. The most commonly used server clusters are that of database servers, file servers, messaging servers and print servers. Each server that exists in a clustered server environment is responsible for owning and managing its own devices. Moreover, each server carries a copy of the OS that is running the other servers of the same cluster.

How Server Clustering Works

Server clustering offers the benefit of reduced outages and downtime by enabling a server, in a group of servers, to take over in any untoward situation that causes an outage. Let us understand how this is made possible. In server clustering, a group of servers are connected to a single system. Whenever there is an issue and any one of the servers experiences an outage, immediately the workload is redistributed to some other server. This ensures that the client experiences hardly any downtime. In this way clustered servers deliver high availably, scalability and prove to be a very reliable solution for their clients. The servers in a clustered server environment are programmed to work in tandem in order to maintain the cluster configuration’s consistency and to augment data protection.

Why Are Server Clusters Needed?

The deployment of server clusters aids in avoiding downtime for businesses. This is one of the main reasons for using server clustering. Additionally, it helps in maintaining system accessibility, even if there is a critical hardware failure. Moreover, businesses that are experiencing performance degradation can ensure faster as well as unhindered performance for their high volume workloads.

Various Types of Server Clusters

Server clusters are mainly of four types. Each of these caters to different infrastructure requirements and business objectives. These are HA (High Availability) Server Clusters, Load Balancing Clusters, High Performance Clusters, and Clustered Storage. Let us shed light on each of these types individually.

HA (High Availability) Server Cluster

A High Availability Server Cluster is an ideal option for websites that experience high traffic, such as, online stores and applications. It ensures optimal and uninterrupted performance of critical systems. HA server clusters are capable of avoiding single points-of-failure as these are built on hardware and software that are redundant. These server clusters ensure website operation that is continuous and aid in delivering full-time availability. High Availability clusters ensure that there is the least amount of downtime in situations of overload or server failure.

HA Server Clusters have two types of architecture. These are Active-Active and Active-Passive. In an Active-Active cluster all the nodes function simultaneously for balancing loads. In an Active-Passive cluster all the workload is handled by a primary node and another node waits to take over in the situation of downtime. An Active-Passive implementation costs comparatively less than an Active-Active cluster’s implementation.

Scalability, reliability, better maintenance and powerful security with regard to infrastructure along with cost saving due to reduced downtime are offered by HA Server Clusters.

Load Balancing Clusters

In Load Balancing Clusters, user requests are distributed among multiple active nodes. This helps to accelerate operations, reduces congestion in network as well as reduces overload, improves the distribution of workload and ensures redundancy. It enables functions’ separation and workloads’ division among severs for maximizing resources’ availability and utilization.

In this type of server cluster, a load balancing software handles the requests and relays them to different servers, based on an algorithm or a set of rules. This software subsequently handles the outgoing response.

The architecture of Load Balancing Clusters enables the use of multiple links simultaneously. This feature is extremely useful for infrastructure that has redundant communication. Such architecture is deployed a lot in data centers to attain reduction in costs, high-bandwidth data transfers, enhanced availability and scalability.

High Performance Clusters

In a High Performance Cluster, multiple computers are connected to the same network for carrying out a task. These server clusters are connected to clusters of data storage. In this way a complex architecture is formed, which is capable of processing data very swiftly. It is essential for the networking components and storage to keep up with each other, to ensure an effective performance and high-speed transfer of data.

This type of cluster is comparatively less common. High Performance Clusters are used by businesses that have workloads which are resource intensive, in order to attain enhanced performance. Such clusters are extensively deployed in the media industry as well as in research laboratories and are widely used in AI (Artificial Intelligence) technology.

Clustered Storage

A minimum of two storage servers form a clustered storage. It aids in scaling performance. Clustered storage can be deployed in two ways, depending on storage demand and business requirements. One of these involves a tightly coupled architecture, which is directed at primary storage and which contains data separated into extremely small blocks between nodes. The other type of deployment involves a loosely coupled architecture, which is self-contained and which does not store data across nodes. The loosely coupled architecture offers more flexibility but in it performance and capacity get limited to the node’s capabilities. Moreover, this setup does not provide the option of scalability with new nodes, which is possible in a tightly coupled architecture.

Conclusion

Server clusters are very useful and prove to be a fruitful investment in the long run as this solution saves money, manages hardware failure along with website and application failures effectively, ensures high uptime and availability as well as fast response.

Source:https://www.htshosting.org/knowledge-base/server/115/what-are-clustering-capabilities-of-servers