Cluster terminology

[Bodhost-Andy]

A cluster is group of independent computers, also known as nodes, that are
linked together to provide highly available resources for a
network. Each node that is a member of the cluster has both its own individual
disk storage and access to a common disk subsystem, Systems that comprise the cluster operate as a team. When one node in the cluster fails, the remaining node or nodes assume responsibility for
the resources that the failed node was running. This allows the users to continue
to access those resources while the failed node is out of operation3

When installing Exchange 2003 within a Windows 2003 clustered environment,
you may encounter some unfamiliar terms.

Resources
Resources are the applications services, or other elements under the control
of the Cluster Service.

Monitor.
Resource monitor
Resource monitors check their assigned resources and notify the
Cluster Service if there is any change in the resource state.

Resource group
This term refers to a set of dependent resources that are grouped together.
Some resources need other resources to run successfully. For example, a file
share needs a physical disk to hold the data which will be accessed using the
share. These relationships are known as resource dependencies. When one
resource is defined as a dependency for another resource, both resources
must be placed in the same group. If a number of resources are ultimately
dependent on one resource (for example, one physical disk resource), all of
those resources must belong to the same group.
A resource group is the smallest unit of failover. That is, all elements that
belong to a single resource group have to exist on a single node.

Dependencies
Dependencies are used to define how different resources relate to one another. These interdependencies control the
sequence in which the Cluster Service brings resources online and takes
them offline.

Resource states

Resources can exist in one of five states:
– Offline: the resource is not available for use by any other resource or
client.

– Offline Pending: this is a transitional state while the resource is being
taken offline.

– Online: the resource is available.

– Online Pending: this is a transitional state while the resource is being
brought online.

– Failed: there is a problem with the resource that the Cluster Service
cannot resolve.
You can specify the amount of time that Cluster Service allows for specific
resources to go online or offline. If the resource cannot be brought online or
offline within this time, the resource is placed in the failed state.
Resource DLL

[Amelia]

Hey good piece of information. Thanks for sharing Andy.

[tigress]

Thank you for this post, Andy!
My knowledge has been enhanced.
Just a question though...

"A cluster is group of independent computers, also known as nodes, that are
linked together to provide highly available resources for a network. Each node that is a member of the cluster has both its own individual disk storage and access to a common disk subsystem, Systems that comprise the cluster operate as a team. When one node in the cluster fails, the remaining node or nodes assume responsibility for the resources that the failed node was running. This allows the users to continue to access those resources while the failed node is out of operation"

Does the cluster need a separate main server for the data base or does each node contain its own a data base or just the resources?

[Bodhost-Andy]

yes , as I mentioned cluster is a group of commuters so you can use two webserver and one database server. It's all up to depend on what type of architecture you need,each node contain his own a databases.
following are the main reasons to implement clustering association with databases.
* performance, because you can spread process loads across multiple nodes; *you can expect to get reasonable performance across a bigger system
* high availability, more particularly, continuous availability.
Please let me know if you have more doubts.

[centelo]

Why is it then that some people are scared off when they hear the word cluster? If its setup proper from the get go, it should never be a problem then, right?