Organizations put a lot of value on mission-critical servers and rely on them heavily to run their businesses. As a result, server downtime can be very costly. A heavily used e-mail or database server can easily cost a business thousands or tens of thousands of dollars in lost productivity or lost business for every hour that it is unavailable. For every benefit and advantage an organization gains by an IT solution, technology and business decision-makers should also think about how to deal with the inevitable downtime of these solutions.
Server availability is a trade-off between availability and cost. The 24/7/365 pace of global commerce makes uninterrupted IT operations vital to an increasing number of industries, from financial services and logistics to manufacturing and travel and tourism. However, achieving the degree of reliability and availability demanded by mission-critical business requirements is expensive to create and support, both in terms of hardware and software costs. In addition, there is the employee time required to manage the solution. The challenge for organizations is to learn what level of IT service availability is justified by their own price of downtime.
High availability refers to redundancies built into an IT infrastructure that makes it available to users even in the event of a service disruption. Disruptions can be unexpected and range from anything as localized as the failure of a network card on a single server to something as dramatic (and improbable) as the physical destruction of an entire data center. Service disruptions can also be routine and predictable, such as planned downtime for server maintenance.
Failover clustering can be used as a way to achieve high-service availability. A failover cluster is a group of computers working together to run a common set of applications that presents a single logical system to client applications. Computers in the cluster are physically connected by either local area network (LAN) or wide area network (WAN) and are programmatically connected by the cluster software. These connections let services to fail over to another computer in the cluster in the event of a resource failure on one computer or its connections to the network.
Failover clusters in Windows Server® 2008 provide high availability and scalability for mission-critical applications such as databases, messaging systems, file and print services, and virtualized workloads. If a node in a cluster becomes unavailable (such as a result of failure or having been taken down for maintenance), another node in the cluster will provide service. Users accessing the service continue their work and are unaware of any service disruption.
This document describes these new features and improvements for the failover clustering in Windows Server 2008.
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