I am doing an educational project where I have to setup 3 (or more) Windows 2008 R2 servers on a machine running ESXi. I wanted to give myself a head start so I began setting an ESXi environment inside VMware Workstation 8 to create a base installation of Windows to copy. My thought was that it would be fairly easy to just bring the vmdk to my next class and upload it to our ESXi machine. But as I began downloading the vmdk disk image from my ESXi server in vmware, I noticed that it took a very long time. On closer inspection I found out that the vmdk was taking up 40 GB of space even though it is setup to do thin provisioning and the Windows installation only took about 7 GB. When I look at the drive through the datastore browser it tells me the actual size is 7 GB and the provisioned size is ~40 GB. How can it be that the image is so large when I attempt to move it?
You de-thinprovision, so to say, the machine, when you copy it off datastore using VMware GUI. Take a look at this VMware Communities thread for a solution.
I found a way to solve my problem. Simply enable the ESXi shell and tar.gz the folder containing the virtual machine. Then I could download each tar.gz with SCP/HTTP/Datastore browser, and store it for later use. It might not be that usable in a running server environment because you have to shut down the servers to tar.gz them, but for a small test environment like mine it works wonders. Thanks for the suggestions though.
Using NFS may be an option, granted you did not mention NFS at all, but with NFS everything is thin-provisioned by default and allows for very easy migration of VMs. Consider a SAN solution like NexentaStor CE, OpenFiler, FreeNAS all of which make it a snap to setup NFS shares and will not cost you anything.
Many people find that having some or ALL NFS-based datastores is actually advantageous over iSCSI, and in some cases even Fibre-channel, for reasons such as this one.
Using VMware Converter to move the VM will also allow you to preserve the thin provisioning. You can also migrate from thick- to thin-provision disks this way.