Cluster

Computer cluster

In computing, a cluster is a group of interconnected computers (often called nodes or servers) that work together closely. From the outside, they often appear as if they are a single, more powerful system.

The main reason to build and use a cluster is to achieve better performance, higher availability (meaning more reliable, with less downtime), or greater scalability (the ability to handle more workload) than a single computer could provide on its own.

Imagine you have a big task, but one person isn't fast enough, or if they get sick, the task stops. A cluster is like having a team of people work on the same task or set of tasks. If one person gets sick, another can take over, and the team can finish the work faster together.

How Clusters Work

Clusters rely on three main things:

1. **Multiple Computers (Nodes):** These are standard computers or servers, often with similar hardware, that are linked together. 2. **A Network:** The computers are connected by a network, which can range from standard Ethernet to very fast, specialized networks that allow the nodes to communicate quickly. 3. **Clustering Software:** Special Software runs on the nodes to manage them as a single unit. This Software is crucial for distributing tasks, managing resources, handling failures, and presenting the group of computers as one system.

This software makes the group of computers cooperate, so they aren't just independent machines connected by a network, but a coordinated team.

Types of Clusters

Clusters are often categorized based on their primary goal:

• High-Availability (HA) Clusters: These clusters focus on minimizing downtime. If one node in the cluster fails (due to hardware problems, OS) issues, etc.), the clustering Software automatically and quickly shifts the workload to another working node. This process is called failover. The goal is to keep important services running continuously, like critical websites or databases.
• High-Performance Computing (HPC) Clusters: Also known as Beowulf clusters or supercomputing clusters, these are designed for raw processing power. They link many computers together to work on complex computational problems that would take a single computer a very long time (or be impossible). Examples include scientific simulations, weather modeling, and complex data analysis. The work is often broken into smaller pieces that each node works on simultaneously.
• Load-Balancing Clusters: These clusters distribute incoming network traffic or workloads across multiple identical servers. A load balancer (either hardware or Software) sits in front of the cluster and directs requests to the different nodes. This prevents any single server from becoming overloaded, improves response time, and increases the total capacity the system can handle. This is common for busy web servers or application servers.

Primary Goals of Different Cluster Types

Type	Main Focus	How it Works (Simply)	Key Benefit
High Availability	Keeping services running	If one server fails, another takes over	Reduces downtime, improves reliability
High Performance	Solving complex problems quickly	Servers work together on parts of the same large task	Increases speed of computation
Load Balancing	Handling many requests	Distributes incoming work across servers	Increases capacity, improves responsiveness

Advantages of Clusters

• **Better Performance:** By combining the power of multiple machines, tasks can be completed faster (HPC, Load Balancing).
• **Increased Availability:** Services remain accessible even if individual servers fail (HA).
• **Improved Scalability:** It's often easier to add more nodes to a cluster to handle increased workload than to replace a single server with a much larger one (HPC, Load Balancing).
• **Cost-Effectiveness:** Sometimes building a cluster of commodity hardware is cheaper than buying one very large, specialized, fault-tolerant machine.

Disadvantages of Clusters

• **Complexity:** Setting up and managing clustering Software and the interconnected network is more complex than managing a single server.
• **Cost:** While potentially cheaper than one giant machine, you still need to buy, power, and maintain multiple servers and the network infrastructure.
• **Software Compatibility:** Not all Software is designed to run efficiently in a clustered environment, especially for HPC.

Usage Examples

Clusters are used in many areas:

• Large websites and online services (using load-balancing and HA clusters for web servers and databases).
• Scientific research (HPC clusters for simulations and modeling).
• Financial trading systems (HA clusters for critical applications).
• Cloud computing platforms (often built on large clusters of servers).
• Big data processing and analytics.

In summary, a cluster is a powerful way to use multiple computers working together to achieve goals related to performance, availability, or scalability that would be difficult or impossible for a single machine.

See Also

• Server (computing)
• Networking
• High availability
• High-performance computing
• Load balancing
• Failover
• Scalability
• Virtualization (A different way to maximize hardware use)

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The Template is currently placeholder template is used to create citations for material published on the World Wide Web or other online resources that do not fit other citation template types (e.g., online news articles might use Template is currently placeholder). It is intended to provide a standardized and consistent format for citing web pages within articles. - Explanation from a major computing company.

Template:Cite web

The Template is currently placeholder template is used to create citations for material published on the World Wide Web or other online resources that do not fit other citation template types (e.g., online news articles might use Template is currently placeholder). It is intended to provide a standardized and consistent format for citing web pages within articles. - Technical definition and explanation.

Template:Cite web

The Template is currently placeholder template is used to create citations for material published on the World Wide Web or other online resources that do not fit other citation template types (e.g., online news articles might use Template is currently placeholder). It is intended to provide a standardized and consistent format for citing web pages within articles. - Explanation focused on HPC clusters.