分布式与集群的区别是什么

分布式系统与集群的主要区别在于它们的架构目标、节点间协作方式、资源共享模式和扩展性。集群通常指由多台服务器组成的，目的在于提高系统的可用性和扩展性，服务器之间具有相同或相似的配置，它们合作处理计算任务。而分布式系统由空间位置上相隔较远、独立的计算节点组成，这些节点通过网络进行通信和协调，共同完成任务，其着眼于资源共享、计算能力和数据的分布式管理。

集群的主要目的是通过冗余手段来提高系统可用性和容错能力。例如，一个Web服务集群可以由多台服务器组成，每台服务器都运行相同的应用，以便在一台服务器宕机时由另一台服务器接管服务，用户几乎不会感受到服务中断。

一、架构目标的不同

集群的设计目标 primarily focuses on high avAIlability and scalability. The servers within a cluster often run the same application or services, and they operate as a single system. Clustering is commonly used to ensure that critical services can withstand individual hardware failures and can be scaled by adding more servers to the cluster as demand grows.

分布式系统的架构目标

分布式系统, on the other hand, are aimed at utilizing a collection of networked computers to perform tasks that a single machine might not be capable of handling. The goal of a distributed system is to coordinate the use of diverse resources scattered across multiple locations to achieve superior performance, scalability, and to harness the collective power of these resources.

二、节点间协作方式的不同

In a cluster, nodes primarily work together to provide high availability and load balancing. If one node fails, others can take over the work to maintain the service without interruption. The nodes are aware of each other and can distribute the work among themselves to handle more requests simultaneously.

分布式系统中的协作方式

Conversely, nodes in a distributed system may be more autonomous, performing different tasks that contribute to a common goal. They often require complex algorithms for consensus and coordination, and they may not share a common state, unlike a cluster where the state is usually replicated among all nodes.

三、资源共享模式的不同

集群经常共享存储资源，有一个集中的存储系统让所有节点都能访问数据。这帮助它们维护应用程序状态的一致性，从而提高可靠性和可用性。

分布式系统的资源共享

分布式系统 may distribute data across various nodes, where each node operates on its data locally. This can complicate data consistency but allows the system to scale horizontally more efficiently and can improve resilience and overall performance, as data is close to the computational resources.

四、扩展性的不同

A cluster scales primarily by adding more similar or identical nodes to the existing pool of resources. Scaling out a cluster involves increasing the number of nodes to support more concurrent users or to improve fault tolerance.

分布式系统的扩展性

分布式系统, meanwhile, is explicitly designed to scale out across various machines and locations. They can incorporate heterogeneous hardware and are usually better suited for the addition of disparate resources. The ability to scale out seamlessly is a significant advantage of distributed systems.

五、设计复杂性的不同

Clusters tend to have a simpler design when compared to distributed systems because the environment is more controlled, and components are more uniform. The software stack and the interconnection between cluster nodes are often easier to manage and maintain.

分布式系统的设计复杂性

On the contrary, 分布式系统 often encounter a wide range of complexities due to the variability in node capabilities, network latency, and the need for more sophisticated coordination protocols to ensure consistency across the system. Such systems can be more challenging to design, implement, and debug.

六、不同的实际应用场景

集群 is commonly used in environments where service continuity and high availability are critical. Web server clusters, database clusters, and high-performance computing clusters are typical examples where clusters are employed.

分布式系统的应用场景

分布式系统 is utilized when tasks are inherently distributed and require the cooperation of many machines that may not be in close proximity. Examples include cloud computing platforms, the global Domain Name System (DNS), and large-scale data processing frameworks like Hadoop.

Understanding these differences between distributed systems and clusters is crucial for designing robust, scalable, and resilient architectures that meet specific business or technical requirements. Each approach has its strengths and trade-offs, and choosing the right one depends on the challenges at hand.