Windows Server 2008 Changes in Failover Clustering

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The set of changes introduced in Failover Clustering since the release of Windows Server 2008 is far more impressive. SQL Server 2008 can be benefitted out of these features. The most relevant are the following:

Entirely Redesigned Administrative Interface Based on Microsoft Management Console 3.0

Windows Server 2008 R2 introduces PowerShell support, which in addition to automation capabilities, allows read-only access to cluster configuration settings, which was not previously possible. A variety of new logging, eventing, and performance monitoring options are among other manageability improvements.

Radical Shift in Hardware Certification Process

In previous clustered implementations, based on Windows Server 2003 or earlier, entire configuration had to be Windows Hardware Quality Lab-certified and listed as a Cluster Solution in the Windows Server Catalog. This drove up the cost, since it required hardware vendors to perform tests of end-to-end clustering solutions, which had to be repeated following individual firmware releases. It also limited flexibility, forcing admins to choose specific set of components. This is no longer the case. Starting with Windows Server 2008, components require only OS-level certification. The suitability of a custom clustering solution is determined by the Cluster Validation Wizard, which is incorporated into the Failover Cluster feature set. The wizard performs a number of tests, which verify whether an existing multiserver setup qualifies for failover clustering.

New Storage Requirements

Due to the dependency on SCSI-3 persistent reservations for clustered storage (replacing inferior SCSI-2 ReserveRelease commands), support for parallel SCSI has been discontinued starting with Windows Server 2008, leaving Serial Attached SCSI (SAS), iSCSI, and Fibre Channel as the viable options.

Resilient Quorum Model

This eliminates the single point of failure present in the earlier design by relying on a multinode quorum and, optionally (to determine majority in a cluster where an even number of nodes is online), on an additional witness resource, implemented as either a Physical Disk cluster resource or a file share.

More Secure Cluster Service Configuration

The service no longer uses a domain account, but instead, relies on the Local System built-in security principal. This eliminates the need for periodic password changes in cases where their expiration is dictated by corporate policies. More importantly, it prevents the possibility of account lockouts. To provide a security context for domain-level operations, the cluster is represented by an Active Directory computer account known as Cluster Name Object. Similarly, clustered Network Name resources take the form of domain-based Virtual Computer Objects. The existence of these objects facilitate a switch to Kerberos as the primary authentication protocol for cluster-bound communication (in place of NTLM, which becomes the secondary option).

Enhanced Multisite Clusters Capabilities

With the release of Windows Server 2008, it became possible to place cluster nodes on different subnets, eliminating the need for stretched VLANs in multi-site clustered implementations. Such designs, however, are subject to several limitations. This functionality is further augmented by the innovations in quorum design mentioned earlier as well as networking efficiency and reliability improvements.

Hyper-V Integration

The ability to cluster both Hyper-V hosts and guests is reflected by introduction of VM-specific options within the Failover Cluster Manager interface (and, conversely, availability of cluster-specific tasks within the System Center Virtual Machine Manager). Windows Server 2008 R2 offers support for Live Migration (which provides an alternative to VMware VMotion) and, thanks to Cluster Shared Volumes, removes the need to place individual VMs on dedicated LUNs in order to allow for their independent failover.

Enhanced Network Configuration

Cluster nodes no longer need to have static IP settings (if needed, you can assign them via DHCP). In addition, intra-cluster communication is digitally signed and can be encrypted, if desired.

EOF - Windows Server 2008 Changes in Failover Clustering, SQL Server 2012 , 2008 R2 , 2008 , 2005 , 2000

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