If you are running Nested vSAN Original Storage Architecture (OSA) or vSAN Express Storage Architecture (ESA) workloads on top of a physical vSAN OSA setup, you may want to enable the Guest TRIM/UNAMP capability, which would allow your the "inner" (Nested) workloads to pass the TRIM/UNMAP requests down into your physical vSAN OSA deployment for space reclamation.
It was recently observed that storage utilization may continue to increase on a physical vSAN OSA setup even when the Nested vSAN ESA/OSA workloads have already freed up their storage, which is due to the fact that the TRIM/UNAMP commands are not being passed down into the physical vSAN OSA. If you are using vSAN ESA for your physical setup, Guest TRIM/UNMAP is already enabled by default, so this is only applicable if you are using vSAN OSA.
To enable the Guest TRIM/UNMAP capability, you need apply the following ESXi Advanced Setting to your physical vSAN OSA.
