Cluster Chapter 1 Introduction

The Cluster means a Set of computers that works as a 1 network identity.
In Microsoft technology, Microsoft supports 2 technologies in Cluster. The first is a MSCS and the second is a NLBS.

It is designated for High Availability.

Availability = MTTF ./ (MTTF + MTTR)

MTTF is a term of occur a system failure period and MTTR is a term of recovery.
For improve the availability, you should increase MTTF or reduce MTTR.

The Cluster system appears as a single system to network clients.
Clients don't know about that is clustered or not. But a service would be in the second node because of system fail on the first node.