A computer cluster is a group of loosely coupled computers that work together as a single system. Clusters provide improved speed, reliability, and cost effectiveness over single computers. There are three main types of clusters: high availability clusters which provide uninterrupted services if a node fails; load balancing clusters which distribute work across nodes; and parallel processing clusters which solve problems faster through distributed processing. The basic components of clusters are nodes, networks, and applications. Clusters provide benefits like high availability, improved performance, and scalability.

1. Rohit jain Ronak maru
Arya Institute of Engg.&Tech

2.  Introduction
 Types of cluster :-
o High Availability or Failover Clusters.
o Load Balancing Cluster.
o Parallel/Distributed Processing Clusters.
 Cluster Component.
 Cluster Application.
 How Does It Work?
 Cluster benefits

3.  A computer cluster is a group of loosely
coupled computers that work together closely so
that in many respects it can be viewed as though it
were a single computer.
 Clusters are commonly connected through fast local
area networks.
 Clusters are usually deployed to improve speed
and/or reliability over that provided by a single
computer, while typically being much more cost
effective than single computer the of comparable
speed or reliability .

4.  In cluster computing each node within a cluster is an
independent system, with its own operating system,
private memory, and, in some cases, its own file system.
Because the processors on one node cannot directly
access the memory on the other nodes, programs or
software run on clusters usually employ a procedure
called "message passing" to get data and execution code
from one node to another.
 Clusters have evolved to support applications ranging
from ecommerce to high performance database
applications.
 Cluster computing can also be used as a relatively low-
cost form of parallel processing for scientific and other
applications that lend themselves to parallel operations.

6. 1. High Availability or Failover Clusters
2. Load Balancing Cluster
3. Parallel/Distributed Processing Clusters

7.  These clusters are designed to provide uninterrupted
availability of data or services (typically web
services) to the end-user community.
 if a node fails, the service can be restored without
affecting the availability of the services provided by
the cluster. While the application will still be
available, there will be a performance drop due to
the missing node.
 The purpose of these clusters is to ensure that a
single instance of an application is only ever
running on one cluster member at a time but if and
when that cluster member is no longer available, the
application will failover to another cluster member.

10.  This type of cluster distributes incoming requests for resources
or content among multiple nodes running the same programs
or having the same content.
 Both the high availability and load-balancing cluster
technologies can be combined to increase the reliability,
availability, and scalability of application and data resources
that are widely deployed for web, mail, news, or FTP services.
 Every node in the cluster is able to handle requests for the
same content or application.
 This type of distribution is typically seen in a web-hosting
environment.

13.  parallel processing was performed by multiple
processors in a specially designed parallel
computer. These are systems in which multiple
processors share a single memory and bus
interface within a single computer.
 These types of cluster increase availability,
performance, and scalability for applications,
particularly computationally or data intensive
tasks.

14.  The basic building blocks of clusters are broken
down into multiple categories:
1. Cluster Nodes
2. Cluster Network
3. Network Characterization

15.  There are three primary categories of applications
that use parallel clusters:
1. Compute Intensive Application.
2. Data or I/O Intensive Applications.
3. Transaction Intensive Applications.

16.  A user submits a job to the head node. The job
identifies the application to run on the cluster. The
job scheduler on the head node assigns each task
defined by the job to a node and then starts each
application instance on the assigned node. Results
from each of the application instances are returned
to the client via files or databases.

18.  The main benefits of clusters are:
1. Availability
2. Performance
3. Scalability
 These benefits map to needs of today's enterprise
business, education, military and scientific
community infrastructures.