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Overview of Clustering with GSX Server
Overview of Clustering with GSX Server
GSX Server clustering capabilities are ideally suited for development, testing and training applications.
Note: Always rigorously test and review your cluster before deploying it in a production environment.
This section includes:
Clustering is providing a service via a group of servers to get high availability, scalability or both.
For example:
In a Web server cluster where the Web site serves static content, a gateway distributes requests to all nodes according to load. The gateway also redirects requests to remaining nodes if one crashes.
This configuration increases availability and performance over a single-machine approach. Network Load Balancing in Windows 2000 and Windows Server 2003 provides such a service.
In a more complex cluster, a single node might serve a database. If that node crashes, it must restart the database on another node. The database application knows how to recover from a crash. In normal operation, other nodes run other applications.
Microsoft Cluster Service and Veritas Cluster Service provide such a service.
In a typical virtual machine cluster:
Each virtual machine is one node in the cluster.
Disks are shared between nodes.
Shared disks are needed if the application uses dynamic data as mail servers or database servers do.
When using virtual disks, you must preallocate the disk space at the time you create the virtual disk.
There are extra network connections between nodes for monitoring heartbeat status.
There is a method for redirecting incoming requests.
Applications That Can Use Clustering
To take advantage of clustering services, applications need to be clustering-aware. Such applications can be stateless, such as Web servers and VPN servers. Clustering-aware applications often include built-in recovery features, like those in database servers, mail servers, file servers or print servers.
Clustering Software
Available clustering software includes:
Microsoft Clustering Service (MSCS) — under Windows 2000, MSCS provides fail-over support for two to four-node clusters for applications such as databases, file servers and mail servers. Under Windows Server 2003, MSCS provides failover support for eight-node clusters.
Microsoft Network Load Balancing (NLB) — that balances the load of incoming IP traffic across a cluster of up to 32 nodes for applications such as Web servers and terminal services.
Veritas Clustering Service (VCS).
Novell Clustering Services.
Note: These clustering services are tested and supported by VMware only with Windows host operating systems.