Question

Why, exactly, does Calm have to be on a Nutanix cluster?

  • 26 April 2021
  • 4 replies
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Hi.

I’m the first to admit that I read the documentation for Calm a bit too quickly and didn’t really reflect on the meaning of “The Prism Central in which Nutanix Calm is running is registered with the same cluster.” and “Nutanix Calm is supported only on AHV and ESXi hypervisors on a Nutanix cluster.”

After trying and failing to run this on an existing VMware cluster, that the Prism Central/Calm installation doesn’t own, I re-read the documentation and realized that I’d glossed over the actual requirements.

I mention this to clarify that this isn’t a post about unclear documentation or incorrect requirements. I goofed, as simple as that. :)

What I do want to know though is why these requirements exist. I have talked to my contacts at Nutanix and I so far I haven’t got a proper answer to this question.

Can anyone please explain, in detail, why I can’t run Calm on an arbitrary VM?


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@Martin Edelius 

Calm Standalone VM on ESXi  is supported. Please check the  Link . 

Also with respect why these requirements exist for calm enablement on PC VMs running on nutanix clusters, it is required for installing docker volume plugin that is used to create volume group . Calm stores task logs and icons in the created VG.

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Hi @charan-49230 !

Thanks for the reply and for the link, that was not mentioned when I talked to my contacts at Nutanix and I’ll be sure to send it to them. :)

This only confuses things more for me though. If I can run a stand-alone VM with calm on ESXi, why does the Prism Central VM with Calm included use functionality that is only available on a Nutanix cluster?

And why does Calm create VG’s to store logs and icons? That seems like a really complex solution for something that can just be written to disk.

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@Martin Edelius 

 

Good question. There is a limitation on the prism central home disk space usage. if calm stores the logs and icons in same path it leads to disk space issues.

On the other side, calm VM  is a custom build on top of PC with a additional disk of 10 GB that is used to store logs and icons. 

 

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@charan-49230

The reason I’m mentioning this is because it in my opinion is a hindrance to the use of Calm. In my current project we had to do quite a bit of workaround to get PC/Calm to work, and we had to place it on the same cluster it’s managing. Sure, we could use the standalone Calm VM but that isn’t optimal.

To me this sounds like when Dr. Ian Malcolm comments on the scientists creating dinosaurs in Jurassic Park, but instead its Nutanix engineers using docker plugins and VG’s to store logs; “Your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.” ;)

I would like to make some sort of official feature request to make PC/Calm completely standalone so that it can be run anywhere - even on a VM in the cloud.

Thanks for your replies.

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