Q: How do I convert an NTFS formatted volume to ReFS?
A. ReFS is a new file system introduced in Windows Server 2012 to provide the highest level of data integrity and resiliency to failure. However, it doesn't have all the same capabilities as NTFS nor can it be used in all scenarios--for example, ReFS can't be used as the boot or system volume. Before looking to move from NTFS to ReFS, verify the workload is supported on ReFS.
There is no "convert" command to convert a NTFS volume to ReFS. The only way to switch between NTFS and ReFS is to back up all data from the volume, reformat using ReFS, then copy the data back.