What's New in Failover Clustering in Windows Server Technical Preview

A new feature in Failover Clustering, Cluster Operating System Rolling Upgrade enables an administrator to upgrade the operating system of the cluster nodes from Windows Server 2012 R2 to Windows Server Technical Preview without stopping the Hyper-V or the Scale-Out File Server workloads. Using this feature, the downtime penalties against Service Level Agreements (SLA) can be avoided.

What value does this change add?

Upgrading a Hyper-V or Scale-Out File Server cluster from Windows Server 2012 R2 to Windows Server Technical Preview no longer requires downtime. The cluster will continue to function at a Windows Server 2012 R2 level until all of the nodes in the cluster are running Windows Server Technical Preview. The cluster functional level is upgraded to Windows Server Technical Preview by using the Windows PowerShell cmdlt Update-ClusterFunctionalLevel. 

Warning
After you update the cluster functional level, you cannot go back to a Windows Server 2012 R2 cluster functional level.  Until the Update-ClusterFunctionalLevel cmdlet is run, the process is reversible, and Windows Server 2012 R2 nodes can be added and Windows Server Technical Preview nodes can be removed.

What works differently?

A Hyper-V or Scale-Out File Server failover cluster can now easily be upgraded without any downtime or need to build a new cluster with nodes that are running the Windows Server Technical Preview operating system. Migrating clusters to Windows Server 2012 R2 involved taking the existing cluster offline and reinstalling the new operating system for each nodes, and then bringing the cluster back online. The old process was cumbersome and required downtime. However, in Windows Server Technical Preview, the cluster does not need to go offline at any point.

The cluster operating systems for the upgrade in phases are as follows for each node in a cluster:

• The node is paused and drained of all virtual machines that are running on it.
  
  
• The virtual machines (or other cluster workload) are migrated to another node in the cluster.The virtual machines are migrated to another node in the cluster.
  
  
• The existing operating system is removed and a clean installation of the Windows Server Technical Preview operating system on the node is performed.
  
  
• The node running the Windows Server Technical Preview operating system is added back to the cluster.
  
  
• At this point, the cluster is said to be running in mixed mode, because the cluster nodes are running either Windows Server 2012 R2 or Windows Server Technical Preview.
  
  
• The cluster functional level stays at Windows Server 2012 R2. At this functional level, new features in Windows Server Technical Preview that affect compatibility with previous versions of the operating system will be unavailable.
  
  
• Eventually, all nodes are upgraded to Windows Server Technical Preview.
  
  
• Cluster functional level is then changed to Windows Server Technical Preview using the Windows PowerShell cmdlet Update-ClusterFunctionalLevel. At this point, you can take advantage of the Windows Server Technical Preview features.
  
  

For more information, see Cluster Operating System Rolling Upgrade in Windows Server Technical Preview.

Storage Replica (SR) is a new feature that enables storage-agnostic, block-level, synchronous replication between servers for disaster recovery, as well as stretching of a failover cluster for high availability. Synchronous replication enables mirroring of data in physical sites with crash-consistent volumes to ensure zero data loss at the file-system level. Asynchronous replication allows site extension beyond metropolitan ranges with the possibility of data loss.

What value does this change add?

Storage Replication enables you to do the following:

• Provide a single vendor disaster recovery solution for planned and unplanned outages of mission critical workloads.
  
  
• Use SMB3 transport with proven reliability, scalability, and performance.
  
  
• Stretch clusters to metropolitan distances.
  
  
• Use Microsoft software end to end for storage and clustering, such as Hyper-V, Storage Replica, Storage Spaces, Cluster, Scale-Out File Server, SMB3, Deduplication, and ReFS/NTFS.
  
  
• Help reduce cost and complexity as follows:
  
  
  • Is hardware agnostic, with no requirement for a specific storage configuration like DAS or SAN.
    
    
  • Allows commodity storage and networking technologies.
    
    
  • Features ease of graphical management for individual nodes and clusters through Failover Cluster Manager.
    
    
  • Includes comprehensive, large-scale scripting options through Windows PowerShell.
    
    
• Help reduce downtime, and increase reliability and productivity intrinsic to Windows.
  
  
• Provide supportability, performance metrics, and diagnostic capabilities.
  
  

For more information, see the Windows Server Technical Preview Step-by-Step Guide for Storage Replica.

What works differently?

This capability is new in Windows Server Technical Preview.

What's New in Windows Server Technical Preview