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Performance issues on Windows virtual machine with hardware version 13 after upgrading to ESXi 6.5 (2150591)

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After upgrading to VMware ESXi 6.5.0 P01 (build 5146846) or ESXi 6.5.0d (build 5310538), you experience these symptoms:
  • Windows Server 2012 R2/Windows Server 2016 virtual machines respond slowly or appear to be unresponsive.
    Note: Windows 2008 R2 virtual machines are not affected.

  • Applications running on the Windows Guest OS, such as an Exchange or File server run slowly.
  • Virtual machine performance is degraded.


The issue occurs when non-aligned unmap requests are received from Guest OS under certain conditions depending on size and number of non-aligned unmaps.  You may see the issue while deleting large number of small files ( less than 1 MB in size) in the Guest OS. 


This issue is resolved in VMware ESXi 6.5 Update 1, available at VMware Downloads. For more information, see the ESXi 6.5 Update 1 Release Notes.

To work around this issue disable delete notification using one of these methods:
  • Using a registry editor, change this key to 1:


  • Use this PowerCLI command:
    fsutil behavior set DisableDeleteNotify 1

Note: This is a temporary workaround to confirm the issue is seen when the Guest OS sends unmap requests

Additional Information

For more information on using fsutil, see Microsoft Technet - Fsutil behavior.

Note: The preceding links were correct as of July 17, 2017. If you find a link is broken, provide feedback and a VMware employee will update the link.

Request a Product Feature

To request a new product feature or to provide feedback on a VMware product, please visit the Request a Product Feature page.


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