Poor performance with Windows 10/ 2019 1809 on VMFS 6

TL;DR: This bug is still up to date and has not been fixed yet! Some user in the VMTN thread mentioned a hotpatch from VMware, which seems to be pulled. A fix for this issue will be available with ESXi 6.5 U3 and 6.7 U3. The only workaround is to place VMs on VMFS 5 datastores, or avoid the use of snapshots if you have to use VMFS 6. I can confirm, that Windows 1903 is also affected.

One of my customers told me that they have massive performance problems with a Horizon View deployment at one of their customers. We talked about this issue and they mentioned, that this was related to Windows 10 1809 and VMFS 6. A short investigation showed, that this issue was well known, and even VMware is working on this. In their case, another IT company installed the Cisco HyperFlex solution and the engineer was unaware of this issue.

Image by Manfred Antranias Zimmer from Pixabay

What do we know so far? In October 2018 (!), shortly after the release of Windows 10 1809, a thread came up in the VMTN (windows 10 1809 slow). According to the posted test results, the issue occurs under the following conditions.

  • Windows 10 1809
  • VMware ESXi 6.5 or 6.7 (regardless from build level)
  • VM has at least one snapshot
  • VM is placed on a VMFS 6 datastore
  • Space reclamation is enabled or disabled

The “official” statement of the VMware support is:

The issue is identified to be due to some guest OS behavior change in this version of windows 10, 1809 w.r.t thin provisioned disks and snapshots, this has been confirmed as a bug and will be fixed in the following releases – 6.5 U3 and 6.7U3, which will be released within End of this year (2019).

https://communities.vmware.com/message/2848206#2848206

I don’t care if the root cause is VMFS 6 or Windows 10. But VMware and Microsoft needs to get this fixed fast! Just to make this clear: You will face the same issues, regardless if you run Windows 10 in a VM, use Windows 10 with Horizon View, or Windows 10 with Citrix. When VMFS 6 and Snapshots comes into play, you will ran into this performance issue.

I will update this blog post when I get some news.

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Patrick Terlisten

vcloudnine.de is the personal blog of Patrick Terlisten. Patrick has a strong focus on virtualization & cloud solutions, but also storage, networking, and IT infrastructure in general. He is a fan of Lean Management and agile methods, and practices continuous improvement whereever it is possible.

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