How to throttle Storage vMotion bandwith?

I am migrating one large VM (2TB+) from older storage (CX4) to new storage (VNX 5200). When I try to SvMotion it,users notice dramatic performance drop on VM. I suspect that is because new storage is much faster and CX4 is struggling to keep up.

Is there a way to throttle back Storage vMotion? Note that both SANs are Fibre Channel.