Most of my disks are thick, but this is how I inherited things.
I'm not sure about #1... When I do a svMotion, my applications are impacted and moving such a large VM could take a few hours and cause some applications issues.
I think I've determined that when my SAN has more than 5k write IOPS, the SP/CPU is almost at 100%. This seems to cause latency accessing the disks, thus my applications begin to react negatively.
Even when you do a single storage vmotion?
All apps are impacted?
Can you tell me about your storage infrastructure?
have you ran esxtop and checked storage and HBA usage?