What's New in Clustering Technologies
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On This Page
 | Introduction |
| Benefits |
| New Features and Improvements |
| Summary |
Introduction
Clustering services have become increasingly essential for organizations deploying business-critical e-commerce and line-of-business applications.
A cluster is a group of computers working together to run a common set of applications and to show a unified system to the client and application. The computers are physically connected by cables and programmatically connected by cluster software. These connections allow computers to use failover and load balancing, which is not possible with a stand-alone computer.
Windows Server 2003 provides two types of clustering services:
| • | Cluster Service (MSCS) Available only in Windows Server 2003 Enterprise Edition and Datacenter Edition, this service provides high availability and scalability for mission-critical applications such as databases, messaging systems, and file and print services. Multiple servers (nodes) in a cluster remain in constant communication. If one of the nodes in a cluster becomes unavailable as a result of failure or maintenance, another node immediately begins providing service, a process known as failover. Users who are accessing the service continue to access the service, and are unaware that it is now being provided from a different server (node). Both Windows Server 2003 Enterprise Edition and Datacenter Edition will support server cluster configurations of up to 8 nodes. This change was made to allow increased flexibility for deployments: particularly for geographically dispersed cluster configurations, and to support N+I configurations (N active with I spare). N+I will be particularly important for supporting larger Microsoft Exchange Server deployments using Windows Server 2003 into the future. |
| • | Network Load Balancing (NLB) Available in all editions of the Windows Server 2003 family, this service load balances incoming Internet Protocol (IP) traffic across clusters. Network Load Balancing enhances both the availability and scalability of Internet server-based programs such as Web servers, streaming media servers, and Terminal Services. By acting as the load balancing infrastructure and providing control information to management applications built on top of Windows Management Instrumentation (WMI), Network Load Balancing can seamlessly integrate into existing Web server farm infrastructures. |
Benefits
| Benefit | Description |
High Availability | The cluster is designed to avoid a single point-of-failure. Applications can be distributed over more than one computer, achieving a degree of parallelism and failure recovery, and providing more availability. |
Scalability | You can increase the cluster's computing power by adding more processors or computers. |
Manageability | The cluster appears as a single-system image to end users, applications, and the network, while providing a single point-of-control to administrators locally or remotely. |
New Features and Improvements
Building on the foundation established in Windows 2000, the Windows Server 2003 family provides new capabilities and features, making it easier and more efficient to deploy and manage clustering services.
Server Cluster Features
| Feature | Description |
Easy Setup and Configuration | The cluster service is an integral part of the Windows Server 2003 operating system, and no longer an optional component. This enables a server cluster node to be configured without distribution media, and allows a server cluster to be created, or the configuration changed, using Cluster Administration tools from a remote management station. No reboots are required to set up a server cluster configuration. Removing a node from a server cluster is as simple as evicting it from the cluster. Any cluster configuration data associated with the node is deleted automatically, and no reboots are required. When a server cluster node is being configured, the configuration process validates the hardware and software configuration to ensure that any known incompatibilities are detected prior to finalizing the configuration of the cluster service. Many configuration options are given default values to make it easier and quicker to set up a server cluster that conforms to best practices. After it is set up, a working server cluster can be customized using server cluster administration tools. The cluster configuration infrastructure is an open interface that's available to third-party software vendors. This enables applications to seamlessly set up server cluster resources, and change their configuration during a server cluster installation. Server cluster setup is scriptable and available through command line tools, as well as the cluster administrator GUI. |
Larger Clusters Now Supported | In Datacenter Edition, the maximum supported cluster size has been increased from 4-nodes in Windows 2000, to 8-nodes in Windows Server 2003. In Enterprise Edition, the maximum supported cluster size has been increased from 2-nodes in Windows 2000 Advanced Server to 8-nodes in Windows Server 2003. By increasing the number of nodes in a server cluster, an administrator has many more options for deploying applications and providing failover policies that match business expectations and risks. Larger server clusters provide more flexibility in building multi-site, geographically dispersed clusters that provide for disaster tolerance, as well as traditional node and/or application failure. |
Integrates with Active Directory Service | Server clusters running Windows Server 2003 Enterprise Edition or Datacenter Edition integrate with the Microsoft Active Directory® service. This integration ensures that a "virtual" computer object is registered in Active Directory. This allows applications to use Kerberos authentication and delegation to highly available services running in a cluster. The computer object also provides a default location for Active Directory-aware services to publish service control points. |
64-Bit Support | Server clusters are fully supported on computers running the 64-bit versions of Windows Server 2003. Applications that can take advantage of the increased memory space of computers running the 64-bit versions of Windows Server 2003 can also take advantage of the high availability offered by failover. |
Increased Manageability | When server clusters are used with storage infrastructures that allow dynamic volume growth, the cluster disks can be expanded dynamically online, with a new in-the-box tool called DiskPart. |
Easy Resource Configuration | It's simpler to set up clustered printers, and the process for setting up the Microsoft Distributed Transaction Coordinator (MSDTC) is easier too—it only needs to be configured once to have configuration information replicated to all nodes. Applications can be made server cluster-aware using scripting languages like Visual Basic® Script and JScript®; this makes it easier to write specific resource add-ins for applications that can be monitored and controlled in a server cluster. Resource-specific properties are also supported; this allows resource scripts to be used to store server cluster-wide configuration information which can be used and managed the same way as any other resource. Microsoft Message Queuing (MSMQ) support has been enhanced to include support for triggers. This allows highly available applications to be built based on all of the features provided by the reliable messaging infrastructure. |
Network Enhancements | Server clusters take advantage of important network enhancements. Enhanced logic for failover is now supported when there has been a complete loss of internal (heartbeat) communication; and the network state for public communication of all nodes is now taken into account before the quorum ownership decision is made. Media sense detection provides better failover protection. Because media sense is disabled by default, the network role is preserved and all IP address-dependent resources remain online. Multi-cast heartbeats is automatically selected—if a server cluster is large enough, and the network infrastructure can support multi-cast between the cluster nodes. If multicast communication fails for any reason, internal communications revert to unicast. In any event, all internal communications are signed and secure. |
Improved Storage Capabilities | Server clusters take advantage of powerful storage capabilities. Volume mount points are now supported on shared disks and work on failover, providing a flexible file system namespace. Client-side caching (CSC), also known as Offline Files, is now supported for clustered file shares and lets a client computer cache data stored on a clustered share. The improved Distributed File System (DFS) now includes: multiple standalone roots, independent root failover, support for active/active configurations, and allows multiple file shares on different machines to be aggregated into a common namespace. Clustering Services has been optimized for storage area networks (SAN), including targeted device resets and storage interconnect requirements. Shared disks can now be located on the same storage interconnect as the boot, pagefile, and dump file disks. This allows a clustered server to have a single—or a single redundant—storage interconnect. NOTE: This is only available where vendors have configured and qualified such configurations. |
Streamlined Operation | Server clusters take advantage of important operational capabilities. Databases and configuration data can be backed up and restored, while enhanced node failover supports failover for clusters with three or more nodes. Group affinity support provides improved performance and availability because applications are failed over to spare nodes before active nodes. Rolling upgrades from Windows 2000 to the Windows Server 2003 family ensure minimum downtime because only one node in a cluster has to be taken offline for upgrading. The cluster service account password can be changed dynamically without having to take cluster nodes offline. Resource deletions are done using Cluster Administrator or with Cluster.exe, without having to take the resource offline. Windows Management Instrumentation (WMI) support is provided in the following areas: cluster control and management, application and cluster state information, and cluster state change events. |
Easier Troubleshooting and Failure Recovery | A number of improvements have been made to server cluster log files to allow easier debugging and troubleshooting. These improvements include: cluster logs; setup logs; error levels; local server time stamp; GUID (globally-unique identifier) to resource name mapping and event log. When a chkdsk is run against a cluster disk, the chkdsk log is kept around, and the status from chkdsk is written to the cluster log. A new diagnostics tool is available in the Resource Kit (ClusDiag) that allows cluster logs and event logs from all nodes in the cluster to be correlated and compared. In the event of a disk failure, the Resource Kit contains a new tool (ClusterRecovery) that allows the disk resource to be reconstructed and the cluster state to be rebuilt. |
New Cluster Topologies | Windows Server 2003 provides the shared disk quorum topology of traditional clusters, as well as a new quorum topology resource called "Majority Node Set" (MNS) which is available in clusters of 3 nodes or more. This quorum model allows server clusters to be built without the dependency of a shared disk as the quorum device. Majority Node Set can be used in conjunction with volume replication software to make it easier to build and configure multi-site, geographically dispersed clusters. |
EFS is Supported on Clustered Disks | Windows Server 2003 supports Encrypting File System (EFS) on clustered (shared) disks. |
Network Load Balancing Features
| Feature | Description | ||||||||||||
Network Load Balancing Manager | This new utility in Windows Server 2003 provides a single point of configuration and management for NLB clusters. NLB Manager can be used to:
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Virtual Clusters | This new feature in the Windows Server 2003 can be used to:
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Multi-NIC (Network Interface Card) Support | The Windows Server 2003 binds NLB to multiple network cards and enables users to:
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Internet Group Management Protocol (IGMP) Support | This new feature limits switch-flooding. (Switch-flooding is caused by the NLB algorithm which requires that every host in an NLB cluster be able to see every incoming packet addressed to the cluster.) IGMP-support conserves network resources by limiting flooding to only those ports on a switch that have NLB machines connected to them. Note: IGMP-support can only be enabled when NLB is configured in multicast mode. |
Summary
Clustering services in Windows Server 2003 will provide dramatic improvements by enhancing existing features and offering important new options.
Installation and setup is easier and more robust. With pre-configurations, remote administration, and established defaults, a basic server cluster can be up and running more quickly, and with fewer reboots.
Integration of clustering services with Active Directory provides many benefits, including: a "virtual" computer object, Kerberos authentication and security, and tighter integration with other services that publish information to Active Directory.
Enhanced network features provide greater failover capabilities and high system uptime. Support and troubleshooting additions allow administrators to pinpoint failures, and possible future issues, using real-time monitoring tools.
For more information about clustering, see Technical Overview of Clustering Services.