Dell Unity: DataStore Full: VMware ESXI Datastore usage does not match Unity Pool usage

Datastore Usage does not match Unity Pool usage.
Datastore is near or at 100% full, causing Data Unavailability.
Datastore is thinly Provisioned from Unity.
Expected production usage does not account for the full Datastore.

Host is running ESXi 5.5 Update 1a 2014-04-19 1746018 (Potentially other ESXi versions from 5.5 to 6.5 could experience this, confirm with VMware Support)
List of ESXi Versions https://kb.vmware.com/s/article/2143832

Since usable space does not match between VMware and Unity, the zeroed space reclamation feature should be investigated from the VMware side. Reference the following VMware KB article for reclaiming space in ESXi 5.5:
https://kb.vmware.com/s/article/2057513

vSphere 5.5 introduced a new command in the esxcli namespace that allows deleted blocks to be reclaimed on thin provisioned LUNs that support the VAAI UNMAP primitive. In this instance, the ESXi host was not reclaiming the deleted blocks, thus filling the datastore.

Engage VMware, quote VMware Knowledge Base Article 2057513 (https://kb.vmware.com/s/article/2057513)

Run a zero space reclaim from the ESXi host, this may alleviate the full the Datastore.