High availability features of Windows Server 2008
Customer that I talk to want to know how they can providing high availability to mission-critical applications, services, and data. When services are down or fail, business continuity is interrupted, which can result in significant losses.
Windows Server 2008 supports two key high-availability features to help organizations meet their uptime requirements for their critical systems: Failover Clustering and Network Load Balancing (NLB). Failover Clustering and NLB in Windows Server 2008 have been improved to offer simplified management and more robust functionality. In addition, Windows Server Backup provides a basic backup and recovery solution in case of hardware failures.
Failover clustering can help you build redundancy into your network and eliminate single points of failure. The improvements to failover clusters (formerly known as server clusters) in Windows Server 2008 are aimed at simplifying clusters, making them more secure, and enhancing cluster stability.
Cluster Validation Tool
By using the new Cluster Validation Tool, you can perform tests to determine whether your system, storage, and network configuration is suitable for a cluster. The Cluster Validation Tool verifies that the nodes meet all of the operating system requirements, that the networks are configured correctly, that there are at least two separate networks on each node for redundancy, and that the storage subsystem supports the necessary Small Computer System Interface (SCSI) commands to handle cluster actions.
Once validated by the Cluster Validation Tool, the installation has been streamlined so that administrators can set up a cluster in one step. The cluster installation is completely scriptable, enabling administrators to automate cluster deployments.
When migrating a clustered service from one cluster to another, cluster settings can be captured and copied to another cluster. This reduces the time it takes to build the new cluster and configure the services.
Cluster Management and Operations Improvements
The cluster management interface has been optimized to make managing the cluster easier and more intuitive. Cluster management can be performed from the command line as well as the Windows Management Instrumentation (WMI) management console. Managing clustered shared folders is now easier to do because it can create customized views to quickly see which shared folders are clustered and which cluster a shared folder is available on.
Backup and Restore Improvements
Full integration with the Volume Shadow Copy Service makes it easier to back up and restore cluster configurations.
Cluster Infrastructure Improvements
The cluster quorum contains the configuration settings for the entire cluster. With Windows Server 2008, you can configure a cluster so that the quorum resource is not a single point of failure by using the majority node set or a hybrid of the majority node set and the quorum resource model. The cluster service can also isolate DLLs that perform actions incorrectly to minimize impact to the cluster, as well as verify consistency among copies of the quorum resource.
Administrators have better control and can achieve better performance with storage than was possible in previous releases. Failover clusters now support GUID partition table (GPT) disks that can have capacities of larger than 2 terabytes, for increased disk size and robustness. Administrators can now modify resource dependencies while resources are online, which means they can make an additional disk available without interrupting access to the application that will use it. And administrators can run tools in Maintenance Mode to check, fix, back up, or restore disks more easily and with less disruption to the cluster.
Networking has been enhanced to support Internet Protocol version 6 (IPv6) as well as Domain Name System (DNS) for name resolution, removing the requirement to have WINS and NetBIOS name broadcasts. Other network improvements include managing dependencies between network names and IP addresses: If either of the IP addresses associated with a network name is available, the network name will remain available.
Internet Protocol security (IPsec) can be used between clients and the cluster nodes, as well as between nodes so that you can authenticate and encrypt the data. Access to the cluster can also be audited to determine who connected to the cluster and when.
Network Load Balancing
Network Load Balancing (NLB) allows you to distribute TCP/IP requests to multiple systems in order to optimize resource utilization, decrease computing time, and ensure system availability. NLB has been improved in Windows Server 2008, including:
Next Generation TCP/IP
The TCP/IP protocol suite has been completely redesigned for Windows Server 2008. Internet Protocol version 4 (IPv4) and Internet Protocol version 6 (IPv6) are both supported natively by Windows Server 2008. NLB extends full support to IPv6 for all communication while maintaining IPv4 support.
Multiple IP Address Support
Each node in your NLB cluster can now have multiple dedicated IP addresses.
Microsoft ISA Server Integration
Microsoft ISA Server can support your mixed IPv4 and IPv6 infrastructure by allowing multiple IP addresses for each NLB node where IPv4 and IPv6 clients are used. ISA Server can also provide intrusion detection services to protect your NLB cluster.