i've got a question about Expanding a VM disk in vCloud Director v9.5. We have several vDC datastores available.
If I edit the properties of a VM and increase the disk size, then vCloud Director automatically performs a Storage vMotion and places the vmdk on another datastores even if the original datastore has plenty of free space.
Is this intended behaviour? Is it possible to configure vCloud Director so that if the original datastore has enough free space it leaves the vmdk on the original datastore?
I think what may be happening here is that vCD's placement engine finds a "better" solution by putting the disk on the other datastore: it suffices that the other datastore have more free space for this to be true. We currently (I believe but will verify) do not have a soft affinity constraint to tie the disk to its original datastore when feasible (i.e. when that datastore has enough free space to accommodate the disk delta requirement).
VCD's placement engine does *try* to keep items in their current datastore. However, there are many caveats which result in the item being moved. There are also a few known bugs in this area, which have been resolved.
If you could provide logs, as well as information about the request that expands a VM's disk, that'd help us figure out why the disk was moved in your specific case. Depending on whether this is a case we've already encountered, or a new scenario we haven't covered, we can either suggest an upgrade to a build that should resolve your issue, or try to address it in a future release.