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Vsphere HA - Admission Control:

jskfan
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Last Modified: 2020-03-05
Vsphere HA - Admission Control:

Any Expert to explain the options of the Admission Control shown below:

a

for instance if we put 0 in : Host  Failures Cluster tolerates
the meaning of the options in : Define host failover capacity by
Performance Degardation VM tolerates

Thank you
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Andrew Hancock (VMware vExpert / EE Fellow)VMware and Virtualization Consultant
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Commented:
checked those links.. just general concept


 for instance if we put 0 in : Host  Failures Cluster tolerates

there will be no reservation of resources for the hosts, they can provide up to 100 % of resources available

and  if one ESX fails, then VMs that can be restarted on other ESX hosts they will be restarted and the ones that do not find enough Resources will not be restarted. ?

for other options:

Cluster Resources Percentage: this is clear
Slot Policy (Power on VMs) : this is NOT clear

Dedicated Failover Hosts : I believe they mean by putting ESX host as spare, it will not be used at all unless one of the ESX hosts in production fails

Performance Degradation VMs tolerate :  is the degradation on the VM or on the ESX host ? I believe they mean degardation on the ESX Host
System Engineer
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Commented:
hi,

my comments :

checked those links.. just general concept
well this link IS the editor documentation describing each option in detail, with other links in it
Plz take some time to read it

for instance if we put 0 in : Host  Failures Cluster tolerates
you cannot put it to 0 AFAIK
It would be useless, admission control enable with 0 is equal to disable

Slot Policy (Power on VMs) : this is NOT clear
answer in a link of the link..
https://docs.vmware.com/en/VMware-vSphere/6.7/com.vmware.vsphere.avail.doc/GUID-85D9737E-769C-40B6-AB73-F58DA1A451F0.html
But I admit this is not entirely clear for me too, and AFAIK this is not oftenly used

Dedicated Failover Hosts : I believe they mean by putting ESX host as spare, it will not be used at all unless one of the ESX hosts in production fails
yes, I never seen it used too, it is obvious why
But there should be some use cases...

Performance Degradation VMs tolerate :  is the degradation on the VM or on the ESX host ? I believe they mean degardation on the ESX Host
it is explained too in the VMware link provided by Andrew
It means degradation in the cluster
It concerns ressource degradation warning/noticing concerning VMs in your cluster, if you loose ESX host(s)

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Commented:
Thank you Guys...
I will come back to this  topic when I re-use the LAB