Hi Vikash,
Harvest doesn't currently have the ability to collect capacity data from UM 5.2 where 7-mode capacity info lives, nor it is included in default templates to collect it directly from 7-mode controllers. It is technically possible and just wasn't high enough priority for me to code in.
As you mentioned, Harvest does support collection of capacity info from OCUM 6.x for cDOT systems, so hopefully this is sufficient for future needs.
Cheers,
Chris Madden
Storage Architect, NetApp EMEA (and author of Harvest)
Blog: It all begins with data