Since the advent of new technologies globally, there has been a demand for improving data center optimization and efficiency. These advancements have led to the development of server clusters. A server cluster provides a user with several advantages over a regular data center server, such as improved scalability, high availability, increased reliability, and redundancy.
Clustering servers into multiple nodes provides users with reliability, optimized load balancing, system scalability, and a higher availability level than just one server. Clustered servers are used for applications that include printing, databases, file sharing, and messaging servers.
With clustered servers, your data is protected. These servers are programmed to function together in a cluster to maintain the consistency of cluster configuration over time.
Before undertaking this systemic approach, it is important to understand server clustering capabilities. Server clustering works to protect against outages when used. Outages are caused by software failure, external events on the physical server site, and hardware failure. They are capable of dealing with issues like:
- Application/Service Failures: Clustering servers can deal with application/service failures resulting from critical errors involving software or services that are crucial to the operation of the server or data center. However, application/service failures are also caused by other factors, and they are unavoidable.
- Hardware/System Failures: A server cluster also helps to deal with hardware failures that can affect the smooth running of your services. Hardware/system failures are caused by overheating, poor optimization, or the component reaching the end of its product lifespan. Hardware components affected in this process are CPUs, memory, power supplies, and hard drives.
- Site Failures: Site failures are widespread. Server clusters help deal with site-related problems caused by events outside the data center environment, such as natural setbacks, power disruptions, etc.
Types of Server Clusters
Servers are classified based on their node or clustering system fused with the device responsible for storing configuration data. There are three different types of server clusters.
- Single or Standard Quorum Cluster
A single or standard quorum cluster is one of the most commonly used server clusters. It consists of multiple servers that employ one or more cluster disk arrays for a single connection device known as a bus.
In essence, a server is responsible for managing and owning the individual cluster disk arrays within the cluster. The titular quorum is the system used in determining whether or not each cluster is online and uncompromised. Single or standard quorum clusters are efficient and straightforward to use. Each server has a vote to communicate to the central bus online.
However, the cluster continues to run as long as over 50% of the servers or nodes in a single quorum cluster are online and functional. If more than 50% of the clusters are not responsive, the cluster stops functioning until the specific node issue is resolved.
- Majority Node Set Cluster
The majority node set cluster is similar to single quorum clusters. However, the majority node set cluster is more flexible when configuring remote servers. It works for servers that are located in different geo-locations.
Each node has its copy of the cluster’s configuration data which consistently flows across all nodes. However, the most node set clusters do not need a shared storage bus to function as each node has its storage system for duplicate quorum data locally.
- Single Node Cluster
A single node cluster contains a single node mainly used for testing. Since single-node clusters are used for testing purposes, they are best used as a tool for research and development of cluster applications. However, the use of a single-node cluster is limited by its lack of failover because it’s made with a single node which can cause the unavailability of cluster groups.
How Does Server Clustering Work?
A server cluster is a group of servers working together under a single IP address to provide users with higher availability, scalability, and reliability. Since server clusters are a group of servers connected to a single system, they work together to increase efficiency.
For instance, whenever one of the servers experiences a service outage, server clusters allow another server to take up the operation, redistributing the workload to another server before the user experiences an outage or downtime. In essence, server clusters help users reduce downtime and improve the efficiency of operation rather than shutting down.
In a clustered server environment, each server in a cluster is called a node. However, each node has its own RAM, hard drive, operating system, and CPU resources to command.
They are responsible for managing and owning their components, which means that work can easily be transferred to another server when one server within the cluster fails. Users can easily access server-related resources since their work is uninterrupted.
When we talk about server clusters, it is important to mention the IP address. This is because servers work on IP addresses to function.
What is an IP?
An IP (Internet Protocol) address, also called an internet address or IP number, is a numerical label given to different devices connected to a computer network that uses the IP protocol for communication.
An IP address helps to identify a specific device on a particular network. An IP address acts as an identifier for a device that allows virtual communication between a source and a destination. Two types of IP addresses that currently exist on the internet are IPv4 and IPv6.
Find out more about IPv4 and IPv6.
How to Configure a Server Cluster?
Server cluster configuration requires setting up a shared database and file system for the servers you intend to use.
To set up your servers in a clustered configuration, you have to configure each physical system and connect the servers to the same database and network storage. Then, you can configure the load balancer for the distribution of traffic between servers. This can be done manually or automatically using software.
For your clustered server to work efficiently, you must ensure that each server in the cluster is running the same version of IBM™ UrbanCode™ Deploy, and they must also be connected on the same network. For example, make sure that your firewall rules can communicate well with your servers over HTTPS and JMS.