Cluster Aware Update Feature in Windows Server 2012

by [Published on 9 April 2014 / Last Updated on 9 April 2014]

Tip explains how Cluster Aware Update works in Windows Server 2012.

Cluster Aware Update, sometimes referred as CAU, was first introduced in Windows Server 2012 for failover clusters. This feature automates the software updating process on clustered nodes while maintaining the availability.

How CAU works?

CAU works automatically on cluster nodes running Windows Server 2012 or Windows Server 2012 R2. During the update process, the following events take place:

CAU is an automated feature that enables you to update clustered servers with little or no loss of availability during the update process. During an Updating Run, CAU transparently performs the following tasks:

  • Puts each node of the cluster into “maintenance mode”
  • Moves the clustered roles off the node
  • Installs the updates and any dependent updates
  • Performs a restart if required
  • Brings the node out of maintenance mode
  • Restores the clustered roles on the node
  • Moves to update the next node

Note: Hyper-V VMs are live migrated to available Hyper-V Node in the cluster maintaining the availability of the virtual machines.

About Nirmal Sharma

Nirmal is a MCSEx3, MCITP and was awarded Microsoft MVP award in Directory Services. He is specialized in Directory Services, Microsoft Clustering, Hyper-V, SQL and Exchange and has been involved in Microsoft Technologies since 1994. In his spare time, he offers technical help by writing tips and articles. Nirmal can be reached at


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The Author — Nirmal Sharma

Nirmal Sharma avatar

Nirmal Sharma is a MCSEx3, MCITP and was awarded the Microsoft MVP award in Directory Services and Windows Networking. He specializes in Microsoft Azure, Office 365, Directory Services, Failover Clusters, Hyper-V, PowerShell Scripting and System Center products. Nirmal has been involved with Microsoft Technologies since 1994. In his spare time, he likes to help others and share some of his knowledge by writing tips and articles on various sites and contributing to PowerShell-based Dynamic Packs for www.ITDynamicPacks.Net solutions.

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