How To's Tutorials

Linux / UNIX Clustering (High Availability) Tutorials

Concept of Clustering :


The concept of a cluster is that the cluster itself appears on the outside as a single system. A cluster consists of two or more Real Computers referred to as nodes or members of a cluster. The components of a cluster are commonly, but not always, connected to  each other through fast Local Area Networks.


Clusters are usually deployed to  improve performance and/or availability  over that provided by a single computer, while typically being much more cost-effective than single computers of comparable speed or availability. Clustering is all about the back-end  operations being performed by the  nodes or members which appear to the  outside world as a single computational entity.


Types of Clusters

  • High Performance Clusters
  • High Availability Clusters
  • Load Balancing Clusters
  • Storage Clusters

High Performance Clusters (HPC)


Multiple nodes in cluster perform concurrent calculations. There are two key benefits of High
Performance (or grid) computing :


  • Resilience : As long as even a single member of a cluster is running, services continue to be provided by the cluster.
  • Increased Capacity : The more nodes added to the cluster, the more computing horsepower is available and therefore very powerful computers can be built using commodity hardware.


High Availabilty Clusters (HA)


High-availability clusters  provide  continuous availability of services by  eliminating single points of failure and by failing over services from one cluster node  to another in case a node becomes  inoperative. High-availability clusters are sometimes referred to as failover clusters.


Red Hat Cluster Suite provides high-availability clustering through its High-availability
Service Management component.


Load Balancing Clusters


Load Balancing Clusters operate by having  all workload come through one or more  load balancing front-ends, which then distribute it to a collection of back end servers. If a node in a load-balancing cluster  becomes inoperative, the load balancing software detects the failure and redirects  requests to other cluster nodes. Red Hat Cluster Suite provides load- balancing through LVS (Linux Virtual Server).


Storage Clusters


Storage clusters provide a consistent file system image across servers in a cluster, allowing the servers to simultaneously read and write to a single shared file system. With a cluster-wide file system, a storage cluster eliminates the need for redundant copies of application data and simplifies  backup and disaster recovery. Red Hat Cluster Suite provides storage clustering through Red Hat GFS(Global File System).




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Siddharth R on, 2013-05-15 06:11:59
Nice document ...Thanks
Shyama Nand on, 2013-05-16 13:08:05
The document is very helpful to understand the concepts of cluster but i requesting you , please share cluster configuration documents in step by step method. Thank so much for sharing the cluster concepts.
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