So far, my research have told me (And DO correct me if I am wrong here).

1: Unmap from VMWare on VMFS towards Dell Compellent is fully supported (Though, in 5.5 Unmap needs to me manually executed).

2: Unmap from Windows 2012 or Linux is fully supported directly towards the Compellent array. 

How-ever, using Unmap in a VMWare guest, running in a VMDK file does NOT work due to the SCSI Controller in VMWare does not have unmap functionallity.

The current recommended way to reclaim dead space, in a VMWare environment using thin-provisioned VMDK's is to:

1: NULL out the blocks on guest level (sdelete on windows for example).  (Win2012 supports unmap, but - that does not work in VMWare, ad the SCSI Controller does not provide unmap functionallity)
2: Schrink the VMDK by wither using hole-punch, or by migrating to a datastore with a different block size.
3: Reclaim the space on Compellent using unmap within VMWare towards the LUN.

My question is, are their any "SCSI Controller" for VMWare that supports unmap through VMWare and further down to the Compellent array? Does Dell have  their own "SCSI Controller driver" which is cable of achieving this?