buffalix
Contributor
Contributor

CPU reservation prevents VM powered on

I have VM with 8vCPU and 16000MHz reserved. And on the host it looks like we have enough resource. Still when I try to power it on, it has error like this

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Host

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VM

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Looking for a quick answer or direction ,

Thanks a lot.

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5 Replies
a_p_
Leadership
Leadership

You've likely set Adminssion Control settings to default settings, where Slot Sizes com into play.

The hosts resources are divided into slots for CPU, and RAM, where the slot size equals the maximum reservation on anyone VM. Each VM will then be counted with a multiple of these reservations, even if it doesn't require it. With 64GB RAM reservation, and 256GB on the host, Admission Control will likely not allow more than 3-4 VMs to be powered on.

André

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buffalix
Contributor
Contributor

That reminded me, thanks!

But I could not find the slot information in web client any more. quick hint?

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depping
Leadership
Leadership

you can find it under vSphere Availability aka High Availability >> Admission Control (I would recommend changing the admission control policy to "percentage based" instead. But why on earth do you set a reservation that high?

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buffalix
Contributor
Contributor

This is interesting. First of all, I did not have admission control enabled so why it looks like it is still enforced?

For troubleshooting purpose, I enabled admission control to see the "advanced runtime info", It looks like we ran out of slot way before I was not able to power on this problematic VM.  So why did not I have this problem until now?

Thanks

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a_p_
Leadership
Leadership

First of all, I did not have admission control enabled so why it looks like it is still enforced?

AFAIK Admission Control is enabled by default as soon as you enable HA.

For troubleshooting purpose, I enabled admission control to see the "advanced runtime info", It looks like we ran out of slot way before I was not able to power on this problematic VM.  So why did not I have this problem until now?

The slots were recalculated after you created the problematic VM (precisely, after setting the reservation). Already powered on VM are not affected by this, and will continue to run. Admission Control only restricts you from powering on additional VMs.


André

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