Memory: Total Reservation Capactiy vs. Total Cluster Capacity

[jk_sui]

Hi guys

I am a bit on a lumb here.

In a vSphere vSAN Cluster (Verison 6.7) I see the following:

Memory Reservation Details

Cluster Total Capactiy                      958.42 GB

Total Reservation Capacity               691.22 GB

Used Reservation                             644.52 GB

Available Reservation                       46.7 GB

Admission Control is turned off for now.

Can anyone tell me, why my "Total Reservation Capacity" is about 270 GB shy of the "Total Cluster Capacity"?

I dont get it, I dont have admission control or anything else (I know of) enabled that would lead to availability constraints.

And it does not make sense in regards to FTT as well. As one host has 192GB RAM configured.

Thanks very much, any help is appreciated.

Best regards

Jonas

[jk_sui · Accepted solution]

We found a KB which explains the vSAN Overhead.

With other overhead in mind, it explains our situation.

VMware Knowledge Base ​

Just in case anyone else has the same question.

Cheers

Jonas