My current environment for
$corp_overlords$ is set up in a hub-and-spoke model with a technologically well-endowed home office hub (SAN, bladecenter/bladesystem ESXi cluster, fiber internet connection, etc.) connected to a number of remote site spokes that are not so well off, and typically contain single ESXi host server and connect to the home office hub via a T1. All traffic originating at any remote site routes back to the home office over a "MPLS network" (which is really just a T1 connecting the remote site to the home office).
At the home office, on the SAN, we have a number of VM templates that I have created to deploy VMs from. They are stored in an NFS volume, that is a vSphere datastore, attached to the home office datacenter object within vSphere.
Each remote site has a corresponding vSphere datacenter object, containing a datastore object that's connected to the locally-attached storage on the ESXi host server physically located at the remote site.
As these VM templates exist on the NFS volume, they occupy ~ 40 GiB (thin-provisioning). As files on NTFS (or a Linux FS), they occupy ~100 GiB.
How should I copy this 40 GiB of thin-provisioned data (that occupies 100 GiB of filesystem space) between my sites?
I am under the constraints that I have approximately 5 days to do so, and cannot interfere (noticeably) with "normal network traffic."