Windows Clustering
Clustering is the connection of multiple computers together in such a way that to the outside world, the cluster appears to be a single system. Each computer in a cluster is referred to as a node.
Business suffers when work stops because of critical service is offline. A properly installed and configured cluster provides continued operation during hardware failure, software failure, and/or planned maintenance. Ability to recover from failed server hardware and failed software is the main benefit of clustering.
Windows Server 2003 clustering consists of two different technologies: Server Cluster and Network Load Balancing (NLB). Each of these technologies can be used to provide high availability for different types of services.
Server Cluster is primarily used to provide availability for mission critical applications through fail-over. It is typically used for databases, e-mail services and custom applications. Windows 2003 supports server clusters of up to eight nodes. Most clustered applications, and their associated resources, are assigned to one cluster node at a time. Node failure in a cluster is detected by the absence of heartbeats from that node. If a node fails to transmit a heartbeat packet for a designated period of time, that node is considered to have failed and the remaining nodes will takeover the work load of the failed node. In this case, the clustered application will be started on remaining nodes. Client requests are immediately redirected to the backup cluster node and the impact of the failure will be minimized.
The NLB service provides a means for load balancing TCP/IP traffic among multiple nodes in an NLB cluster. It manages the incoming traffic and balances it out to the servers participating in the cluster. For example, in the case of a high-traffic web site, when a Web page request is sent to a "manager" server, it will forward this request to one of the server in the cluster. Such implementation allows traffic to be handled more quickly.
Windows 2003 supports NLB clusters of up to 32 nodes. Typically, NLB is used to provide high availability for applications that need client requests distributed across nodes in a cluster such as Web servers, firewalls and proxy servers.
In summary, clustering services in Windows Server systems offer failover capabilities and high system uptime.
Business suffers when work stops because of critical service is offline. A properly installed and configured cluster provides continued operation during hardware failure, software failure, and/or planned maintenance. Ability to recover from failed server hardware and failed software is the main benefit of clustering.
Windows Server 2003 clustering consists of two different technologies: Server Cluster and Network Load Balancing (NLB). Each of these technologies can be used to provide high availability for different types of services.
Server Cluster is primarily used to provide availability for mission critical applications through fail-over. It is typically used for databases, e-mail services and custom applications. Windows 2003 supports server clusters of up to eight nodes. Most clustered applications, and their associated resources, are assigned to one cluster node at a time. Node failure in a cluster is detected by the absence of heartbeats from that node. If a node fails to transmit a heartbeat packet for a designated period of time, that node is considered to have failed and the remaining nodes will takeover the work load of the failed node. In this case, the clustered application will be started on remaining nodes. Client requests are immediately redirected to the backup cluster node and the impact of the failure will be minimized.
The NLB service provides a means for load balancing TCP/IP traffic among multiple nodes in an NLB cluster. It manages the incoming traffic and balances it out to the servers participating in the cluster. For example, in the case of a high-traffic web site, when a Web page request is sent to a "manager" server, it will forward this request to one of the server in the cluster. Such implementation allows traffic to be handled more quickly.
Windows 2003 supports NLB clusters of up to 32 nodes. Typically, NLB is used to provide high availability for applications that need client requests distributed across nodes in a cluster such as Web servers, firewalls and proxy servers.
In summary, clustering services in Windows Server systems offer failover capabilities and high system uptime.
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