Very frequently in order to ensure the high availability and business continuity for critical applications and services you need to implement a Failover Cluster running Microsoft. In this article we'll delve into the main innovations introduced with Windows Server 2016 in the failover clustering and analyse the advantages in adopting the latest technology.
Cluster Operating System Rolling Upgrade
In Windows Server 2016 introduces an important feature that allows you to upgrade the nodes of a Hyper-V cluster or Scale-Out File Server from Windows Server 2012 R2 to Windows Server 2016 without any disruption and avoiding to stop it hosted workloads.
The upgrade process involves these steps:
- Put the node that you want to update paused and move all the virtual machine or the other workloads on the other nodes in the cluster
- Remove the node from the cluster and perform a clean installation of Windows Server 2016
- Add the node Windows Server 2016 the existing cluster. By this time the Mixed mode cluster with both Windows Server nodes 2012 R2 and nodes Windows Server 2016. In this connection it is well to specify that the cluster will continue to provide the services in Windows Server 2012 R2 and will not be yet available features introduced in Windows Server 2016. At this stage you can add and remove nodes is Windows Server 2012 R2 and nodes Windows Server 2016
- Upgrading of all the cluster nodes in the same way as previously described
- Only when all cluster nodes have been upgraded to Windows Server 2016 You can change the functional level to Windows Server cluster 2016. This operation is not reversible and to complete it you must use the PowerShell Update-ClusterFunctionalLevel. After you run this command you can reap all the benefits introduced in Windows Server 2016 stated below
Windows Server 2016 introduces the ability to configure the cluster witness directly in Microsoft Azure cloud. Cloud Witness, just like the tall types of witness, will provide a vote by participating in the calculation of quorum arbitrary.
Figure 1 – Cloud Witness in Failover Cluster Manager
Configuring the Cloud Witness involves two simple steps:
- Creating a subscription to an Azure Storage Account that you will use Azure Cloud Witness
- Configuring the Cloud Witness in one of the following ways
Failover Cluster Manager
Figure 2 – Cloud Witness Configuration Step 1
Figure 3 – Cloud Witness Configuration Step 2
Figure 4 – Cloud Witness Configuration Step 3
The use of Cloud Witness gets the following benefits:
- Leverages Microsoft Azure eliminating the need for an additional separate data center for certain cluster configurations
- Working directly with a Microsoft Azure Blob Storage canceling this way the administrative effort required to keep a virtual machine in a public cloud
- The same Microsoft Azure Storage Account can be used for multiple clusters
- View the mole little data that is written to the Storage Account service charge is ridiculous
Site-Aware Failover Clusters
Windows Server 2016 introduces the concept of clustered failover site-aware and is able to gather groups of nodes in a cluster based on the geographical location configuration stretched (site). During the lifetime of a cluster site-aware placement policies, the heartbeat between nodes and failover operations and calculation of the quorum are designed and improved for this particular cluster environment configuration. For more details about I invite you to consult the article Site-aware Failover Clusters in Windows Server 2016.
Multi-domain and workgroup Cluster
In Windows Server 2012 R2 and in previous versions of Windows, all nodes in a cluster must necessarily belong to the same Active Directory domain. With Windows Server 2016 removes these barriers and provides the ability to create a Failover Cluster without Active Directory dependencies.
In Windows Server 2016 supports the following configurations:
- Single-domain Cluster: clusters where all nodes are in the same domain
- Multi-domain Cluster: cluster composed of nodes joined to different Active Directory domains
- Workgroup Cluster: cluster with nodes in WFWG (not joined to a domain)
In this regard it is good to specify what are the supported workloads and its limitations to Multi-domain and Workgroup cluster:
Recommended SQL Server authentication.
Supported, but not recommended
Kerberos authentication (not available in these environments) is the recommended authentication protocol Server Message Block traffic (SMB).
Supported, but not recommended
Does not support Live Migration, but only the Quick Migration.
|Message Queuing (MSMQ)
Message Queuing save property in AD DS.
Diagnostic in Failover Clustering
In Windows Server 2016 the following innovations have been introduced to facilitate troubleshooting if problems arise cluster environment:
- Several improvements have been made to the cluster log (as the information about the Time Zone and the channel DiagnosticVerbose) making it more easily accessible and more information. For more details about I invite you to consult the article Windows Server 2016 Failover Cluster Troubleshooting Enhancements – Cluster Log
- A new dump file of type Active memory dump, useful Hyper-V clusters, can filter out many pages of memory allocated by virtual machines. This mechanism then generates a file memory.dmp of considerably smaller. More details can be found in Windows Server 2016 Failover Cluster Troubleshooting Enhancements – Active Dump
SMB Multichannel and Multi-NIC Cluster Network
In Windows Server 2016 There are several new features in the network regarding the clustered environment that help ease configuration and get better performance.
The main benefits introduced in Windows Server 2016 can be summarised in the following points:
- SMB Multichannel is enabled by default
- Failover cluster can recognize automatically the NIC attested on the same subnet as the same switch
- A single resource IP Address is configured for each Access Point Cluster (Zip code) Network Name (NN)
- The network with Link-Local IPv6 addresses only (FE80) are recognized as private networks (cluster only)
- The cluster validation does not report more warning messages in case there are more NIC attested on the same subnet
For more information I refer you to the Microsoft documentation: Simplified SMB Multichannel and Multi-NIC Cluster Networks.
Windows Server 2016 introduces major changes in the Failover Clustering making the solution more flexible and opening up new configuration scenarios. Furthermore the upgrade process allows us to easily update existing clusters to take advantage of all the benefits introduced by Windows Server 2016 for different workloads.