How about forcing the first and last block on device when groupoffloading is used?

**Is your feature request related to a problem? Please describe.**
When group offloading is enabled, the offload and onload cannot be streamed between steps and this is really a big time comsuming problem.

**Describe the solution you'd like.**
Is it possible to add an option that could make the first and last block forced on device to avoid offload and onload?

@a-r-r-o-w Could you please give some help? Thanks so much.