Windows Server 2012 R2 failover clustering: Understanding quorum improvements

Since the release of Windows Server 2012 R2, in October 2013, the place on the set of updates for the new operating system has both cloud server has been said. He has spent most of the attention in the improvement of virtualization.

Window server

But in my opinion cluster fail over improvements were impressive. Updates for installation and configuration functionality, maintenance fail over cluster running Windows Server 2012 R2 do a better overall experience for IT professionals.

Dynamic Witness

The launch of Windows Server 2012 R2 has brought a complete overhaul of the cluster quorum process. In the past election, the quorum model when you create a cluster using a complex decision that requires careful examination was necessary. Depending on the number of nodes in the cluster (an even number or an odd number),you had choose a veritable plethora of quorum models to choose from, including Node Majority, Node and Disk Majority or Node and File Share Majority among others.

Well, the choice was made much easier: you decide whether you need to use a hard disk or a witness File Share Witness only? Unlike previous versions of Windows Server, with the help of a witness for our fail over cluster is now recommended. Gone are the days when a failed disk witness could bring a cluster down.For Windows Server 2012 R2, which we simply a witness, if we our cluster, which then decides whether it is necessary, the witness or not. Therefore, if we have two members of our group (or any even number), the File Share Witness or volume is given a vote, if we have to keep an odd number of votes to get a request a cluster.If we then add a third member to our cluster (or an odd number), the witness voice is removed because it is no longer needed.

Tie Break for 50% Node Split

Consider a more complex example with a cluster consisting of four members. Respectively with one voice, along with a witness who has a voice if the light is off then one of the members of the group selected, and your voice will be deleted. This leaves us with a cluster that has three votes, and reaches the odd number of votes required to keep our group. Especially This dynamic feature is useful for geographically dispersed clusters.If a four-node cluster is divided into two sites to witness file sharing is turned off, a node is selected and your voice will be removed.Again,we are left with three votes, and the group is maintained. If the next cluster connectivity, which would remain the two sides were then loosely two votes and keep the group running.Although this behavior is automatic, you can what influence the choice of cluster member loses my voice Lower Quorum Priority Node ID with the new property. The assignment of this property to a node in the Disaster Recovery (DR), we can ensure that our main site stays up.

Force Quorum Resiliency

There may come a time when we have a DR site Force Quorum is not connected by a majority, and is at this time. For example, your main site, with three votes your website has failed and DR with two votes have not automatically brought online because it has enough votes. In a cluster of Windows Server 2012 R2, you can use the Cluster service with the / fix quorum (also known as CF modifier / known) to start, then this partition as the authority for the cluster.

If the network connection is restored, you can bring the three nodes on the main site back online, the clusters which automatically reconnect without intervention. In Windows Server 2012 connectivity is turned once, which would have failed/prevent Default to start server with  modifier quorum new,The above examples show some of the major improvements are now available, I hope you find them useful. If you have questions or want more information please feel free to leave a comment below.

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