Failover Clustering in Windows Server 2012 R2 – Tie Braker for 50% node split

Beside having ability to use Dynamic quorum for Failover clusters, clustering in Windows Server 2012 R2 is enhanced with one more very interesting functionality.
The cluster is now able to automatically adjust running node’s vote status in order to keep total number of votes in the cluster at odd number. This feature is called Tie breaker for 50% node split and it works together with dynamic witness functionality. Dynamic witness functionality is used to adjust the value of quorum witness vote. For example, if you have a cluster with even number of nodes and a file share witness, if the file share witness fails, cluster will use dynamic witness functionality to automatically remove the vote from file share witness.
However, since the cluster now has even number of votes, cluster tie breaker will randomly pick a node, and remove it quorum vote to maintain odd number of votes. If the nodes are evenly distributed in two sites, this will help to maintain cluster functional in one site. In previous Windows Server versions, if both sites have equal number of nodes and file share witness fails, both sites will stop the cluster.

If you want to avoid node being picked randomly you can use LowerQuorumPriorityNodeID property to predetermine which node will have its vote removed. You can set this property by using following Powershell command:

(Get-Cluster).LowerQuorumPriorityNodeID = 1

,where “1” is the example node ID for a node in the site that you consider less critical.
This will be very nice to use with DR scenarios.

Author: ddamir

Damir Dizdarevic is a b.sc.math and IT professional. He works as a manager of MS CPLS Learning Center in Logosoft Sarajevo, and as a lecturer and author of MOC courses. Occasionally, he also works as a system designer for complex enterprise environments. He is a founding member and president of Bosnian Microsoft Community. He has been working with Microsoft platforms for the last 17 years and he is particularly specialized in Windows Server, Exchange Server, mobility and virtualization. Microsoft awarded him with the Most Valuable Professional – MVP status for his outstanding contribution in sharing knowledge about Microsoft Server products, large number of lectures he delivered, and for his high technical competence. Damir owns several technical certificates (MCSE, MCTS, MCITP, and MCT) for Windows Server 2012, 2008 R2, Exchange Server 2010, Security and Hyper-V. He is regular presenter on conferences in ex-Yu region. On Microsoft Sinergija conference, for previous 7 years, each time he was graded as one of top three speakers. On a Bosnian MS conference, he is the best speaker for last two years. He is also a regular and highly graded presenter on other Microsoft conferences in region such as NT Conference (Slovenia), Microsoft Vizija (Macedonia), Microsoft Windays (Croatia), MS Technet, Mobility Day, KulenDayz etc. Damir is one of very few trainers in Europe who works as an author and reviewer of official MOC courses. In previous year, he was authoring courses 20417 (Upgrading Skills to Windows Server 2012), 20414 (Implementing an Advanced Server Infrastructure), 20412( Configuring Advanced Windows Server 2012 Services) and 20410 (Installing and Configuring Windows Server 2012). Also, he was authoring System Center 2012 courses and currently he is working on Exchange Server 2013 and Windows Server 2012 R2 courses. In addition, he has been working for 16 years now as one of the editors of BiH IT magazine INFO, where he published more than 300 technical articles, and he is also writing for the famous Windows ITPro Magazine (some of his work can be found at: http://windowsitpro.com/author/damir-dizdarevic).

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