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You are here: Home / VCSA / How to enable vCenter Server High Availability (VCHA) in vSphere 6.5 w/single ESXi host?

How to enable vCenter Server High Availability (VCHA) in vSphere 6.5 w/single ESXi host?

11.16.2016 by William Lam // 5 Comments

One of the big new features that was introduced in vSphere 6.5, exclusively for vCenter Server Appliance (VCSA), is the vCenter Server High Availability (VCHA) capablilty. Feidhlim O'Leary has an excllent blog post covering what VCHA provides as well as a couple of demo videos on how it works, definitely worth checking out! After upgrading one of my home lab enviornments to vSphere 6.5, I wanted to try out this feature from an educational standpoint and specifically around using new VCHA vSphere APIs.

Like most vSphere Home Labbers, I have limited hardware and if you try to enable VCHA with only a single ESXi host, you will see the following error:

This operation would violate a virtual machine affinity/anti-affinity rule.

enable-vcha-on-single-esxi-host-0
As you might expect, VCHA will automatically provision affinity rules to ensure that the active, passive and witness node are not all running on the same physical ESXi host. For a production deployment this is completely valid but for lab and testing purposes, this might be a tough requirement to satisfy. I was hoping there might be an override option and searching for the word "ha" in the vCenter Server Advanced Settings lead me to an interesting property called config.vpxd.vcha.drsAntiAffinity. This discovery was purely by luck and I had noticed it was set to true by default, so I decided to change it to false and see what would happen.

enable-vcha-on-single-esxi-host-1 
To my surprise, changing this setting worked and I was able to successfully enable VCHA in my lab with all three nodes just running on a single ESXi host 😀

enable-vcha-on-single-esxi-host-2
An alternative solution would be to deploy a 3-Node Nested ESXi cluster which would not require this modification, but my physical ESXi host was limited on memory, only 16GB and would have been a lot slower.

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Categories // VCSA, vSphere 6.5 Tags // VCHA, vSphere 6.5

Comments

  1. *protectedJon Kensy says

    01/31/2017 at 12:39 pm

    Wililam - I am attempting to deploy VCSA HA 6.5 w/ embedded PSC on a two-host cluster. I created a dedicated VLAN for HA network and map to the portgroup during HA config. The config gets to 96% and fails. Is there a log created during HA configuration that I can use to troubleshoot?

    Reply
    • *protectedMmaeso says

      03/08/2017 at 3:15 pm

      It's probably because you need 3 components (vcenter, a replica and a witness) for VCHA, and the wizard creates anti-affinity rules between them. You may have to deploy VCHA manually for this to work

      Reply
  2. *protectedAlmero Rademeyer says

    11/03/2017 at 4:22 am

    Hi William . Would you still protect each of the 3 VCHA nodes with conventional vSphere HA ? I ask as we have an EMC Metro Cluster and I am unable to find documentation on this . In the event of ESXi failure , I don't want vSphere HA restarting my "source" VC and VCHA trying to fail over to target VCHA at the same time would you ? Specifically since my METRO HA and DRS is configured to fail over VMs to other sites by default .

    Any guidance ?

    Reply
  3. *protectedGene Whipple says

    05/17/2018 at 7:27 am

    Hello William,

    Would you know why when I go to vCenter HA on my vcenter server to configure the settings I get an error stating "Error retrieving vCenter HA data"?

    Reply
    • *protectedAndrew Nowicki says

      05/29/2018 at 12:08 am

      Not sure if this helps: https://kb.vmware.com/s/article/2148899

      Reply

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William is Distinguished Platform Engineering Architect in the VMware Cloud Foundation (VCF) Division at Broadcom. His primary focus is helping customers and partners build, run and operate a modern Private Cloud using the VMware Cloud Foundation (VCF) platform.

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