In the article Windows Server 2016: What's New in Failover Clustering all were thorough main innovations introduced with Windows Server 2016 in the failover clustering. In this article we will detail the configuration of the cluster witness in Microsoft Azure cloud, analyzing the possible scenarios and the benefits of this new feature.
Possible scenarios supported by Witness Cloud
Among the supported scenarios that lend themselves more to this type of configuration are:
- Multi-site stretched cluster.
- Failover Cluster that does not require shared storage (SQL Always On, Exchange DAGs, etc).
- Failover Cluster composed of nodes hosted on Microsoft Azure, other public or private cloud.
- Scale-out type cluster File Server.
- Cluster made actually small branch-office.
Cloud Witness configuration
We begin by specifying that a requirement to configure the cluster to use the Cloud Witness is that all nodes that make up the cluster has an internet access to Azure. Cloud Witness in fact uses the HTTPS protocol (door 443) to establish a connection with the Azure blob Storage Service Account.
Configuring the subscription requires a Witness Azure Cloud in which to configure a Storage Account that will be used as Witness and Cloud on which are written the blob file used for the arbitration of the cluster.
From the Azure portal you must create a storage account type Genaral Purpose. For this purpose is incorrect, create it with a performance level standard as they are not necessary for high performance that is provided with the use of SSDS. After selecting the most suitable location and replication policies you can proceed with the process of creating.
Figure 1 – Storage Account creation
After you create your storage account you must retrieve its required access key for authentication, which will be required in configuration steps.
Figure 2 – Account Storage access keys
At this point you can change the settings of the cluster Quorum from Failover Cluster Manager by following the steps below:
Figure 3 – Failover Cluster Quorum Settings Configuration Manager
Figure 4 – Witness Quorum selection
Figure 5 – Selection of Cloud Witness
Figure 6 – Storage Account name and access key
After successful configuration will be present among the various cluster resources also Cloud Witness:
Figure 7 – Cloud Resource Witness
Azure Storage Account is created a container named msft-cloud-witness, within which there will be a single blob file that has as its name the ID I joined the cluster. This means that you can use the same Microsoft Azure Storage Account to set up the different Cloud cluster Witness, where there will be a blob file for each cluster.
Figure 8 – Container inside of the Storage Account and its contents
Advantages of using Cloud Witness
The use of Cloud Witness gets the following benefits:
- Eliminates the need to have an additional separate data center for certain cluster configurations by using Microsoft Azure.
- Cancels the administrative effort required to maintain an additional virtual machine cluster witness role.
- Given the small amount of data written to the Storage Account service charge is ridiculous.
- The same Microsoft Azure Storage Account can be used as a witness to different clusters.
In the Windows Server failover cluster 2016 proves ready for integration with the cloud. With the introduction of cloud cluster systems more easily is possible Witness substantially reducing overall costs for implementing, the management effort and increasing flexibility of architecture cluster.