Load balancing, a component of clustering, divides the amount of work a computer has to do between two or more computers so that more work gets done in the same amount of time. Load balancing can be implemented with hardware, software or a combination of both. balancing, clustering allows database administrators to obtain high availability to support critical applications which would rendered useless in the event of a hardware failure. SQL Server clustering comes in two forms: failover or load balancing.
A failover cluster is typically built with one to four machines, physically configured to share disk storage. Like the other cluster types, all servers within the cluster work together to form one virtual server that provides an application or service to clients.
Failover clusters share disk storage, and therefore are best suited for applications that contain dynamic content, such as databases, file storage, and mail server applications. If you want to cluster an application and the application requires changing content or transaction processing, it must be run on a failover cluster, because a failover cluster is the only cluster model that allows all nodes to share information concerning transactions and changing content.
Load-balanced clusters differ from failover clusters in that they provide not only fault tolerance and reliability, but also scalability and performance. Load-balanced clusters are not limited to a handful of machines that co-operate as a virtual server; machines can be added as needed to increase performance and the system can scale to meet the needs of any application it is providing.
Load-balanced clusters provide high performance due to the number of servers that can be added to the cluster to provide a service or application. They provide scalability through the addition of nodes to the cluster, and they provide fault tolerance by dynamically removing from the cluster machines that fail, so that those machines do not receive client requests.
Load balancing can take a number of different forms such as: log shipping, transactional replication, database partioning and distributed partioning. In addition to choicing which load balancing option is bebst suited for your enviroment other considerations such as scalabity and availability must be taken into consideration. e-mail us to let us know what other guides you'd like to see on SearchSQLServer.com.
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