Saturday, March 17, 2012

Overview Of Forms and Models In Clustering

Forms Of Clustering: There are 3 kinds of forms in clustering.

Failover :
               A fail-over cluster is a group of independent servers that are running Windows Server 2003 or higher versions to increase the availability of services and applications. When a failure occurs on one computer/server in a cluster, resources are redirected and the workload is redistributed to another computer in the cluster. You can use fail-over clusters to ensure that users have nearly constant access to critical server-based resources.

Installation of the fail-over cluster in Windows Server 2008 R2 :
Open Server manager --> In the list of tasks, click Add features ---> In the list of features presented in the wizard, click Failover Clustering ---> and follow the wizard to complete the failover cluster feature installation.

Network Load Balance:
               Network Load Balancing (NLB) is an optional feature in Windows Server® 2008 that load balances network traffic among multiple servers in an Network Load Balancing cluster. NLB is particularly useful for ensuring that stateless applications, such as a Web server running Internet Information Services (IIS), are scalable by adding additional servers as the load increases.There are so many third party tolls available in the market for load balancing one of those are EMC.

Component Load Balance
                Component load balancing (CLB) is a feature of Microsoft Application Center 2000. It is designed to provide high availability and scalability for transactional components. CLB is scalable up to eight servers and is ideally suited to building distributed solutions.

Models of Clustering: 3 types of Models in Cluster, but Windows Server OS is support only Shared Nothing Model and Mirrored Share.

Shared Everything Model : Share both disk, memory and everything wire to wire between nodes in the cluster is shared Everything. Oracle's RAC is inbuilt Inherit support for OS including Windows. SQL Server doesn't support shared everything.

You may ask why Microsoft not providing Shared Everything Model?
What Microsoft is saying is due to Complexity (lots of wiring and stuff), and If DML operations increases, it degrades the performance. Might be we can expect this feature in future editions I am not 100% sure.

Shared Nothing Model : This is what our cluster environment is. A shared nothing architecture (SN) is a distributed computing architecture in which each node is independent and self-sufficient, and there is no single point of contention across the system. none of the nodes share memory or disk storage, every node is independent.

Mirrored Share:  Clustered Shared Volumes (CSV) is a new feature in Windows Server 2008 R2. With Cluster Shared Volumes, multiple clustered virtual machines can use the same LUN while still being able to fail over independently of one another (move from node to node).

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