I assume you meant 16TB disk here.
I’m still not sure if the 4-step process is necessary here.
Why not:
- Robocopy/rsync from your running windows node to your NAS . (Few days/weeks — does not matter. There is no hurry.)
- Shut down node on windows server and run last robocopy/raync wirh /mir or -delete (few minutes)
- Start node on NAS.
Use rsync. It will be faster. However, SMB shall be not much slower, if not faster — what is the bottleneck? Does your zfs server have enough ram and special device? It shall be copying just as fast as to local disk.
The throughput is not an issue, seek latency is, and your NAS is better equipped to hide it than naked single drive. You can also try NFS if you don’t want to setup rsync daemon.
By introducing the intermediary disk you are complicating setup, doubling transfer time, doubling sync passes, and risking data loss — reading NTFS disk on Linux is not advisable.