This is a short update to the past articles on the vCloud Director Cloning process I wrote about a month or so back. In a recent email exchange with Massimo Re Ferre’ it came to light that there is in fact a fast copy process that is invoked in vCloud DIrector PROVIDED all conditions are met. If these conditions are met then vCloud Director will in fact do a Virtual Machine “Clone” from one vCenter Server to another. The conditions that must be met are:
- The optimization is explicitly enabled in the database (Enabled by Default)
- The major versions of source and target VC match
- The datastore is found on both VCs and Clusters
- The source VM does not span datastores
- All VM’s disks have a the same thin provision setting on both OVDCs
- The VM is not a linked clone and does not have snapshots
Now where this will not work quickly is really for item #3. In many cases vSphere Design best practices will have most folks NOT span vCenters or clusters for that matter to see the same storage. In fact in Part 3 of my series, We discussed the very thing that you could have templates on a combined datasotre so VAAI would be used. In fact, if that is the case then you could also take advantage of the fast copy process.
This works for vCenters in a single site or even a stretched cluster for that matter, however two separate sites with completely separate vCenters and clusters will still see the export/import using network copy as I originally detailed. In a sense my initial findings were still accurate, except I was using different vSphere versions so I would never see the fast copy. I also had no shared storage presented between the two vCenters as my goal was to simulate two separate sites under a single vCloud Director instance. So the design consideration remains the same that you could look at a completely shared set of storage for templates in order to take advantage of both VAAI and vCloud Director fast copy process. This process was actually not something I was aware of until today, and is just something else to consider when architecting your vCloud Director deployment. I know Massimo is using this information for a follow on set of documentation around multi-site deployments.