If you are planning to leverage Software Defined Storage, have you consider exploring the Hedvig Solution?
Hedvig is a Software Defined Storage solution offered by Commvault, it Simplifies and consolidate your infrastructures with a unified solution for block, file and object storage.
As a Scale-out-solution it can go from 3 Nodes to thousands of Nodes (depending on the business needs).
The solution offerring is tightly integrated with the Commvault eco-system and has many upcoming changes that will make it fit into any backup workload.
I would recommend to engage your Account Rep to have further discussion.