I tried out Rclone to see if it would be a suitable cross platform alternative to mergerfs for a windows linux duel boot. It all seemed to work just how I expected. My set up was like so.
X + Z put in a union mounted on R
E drive, containing data I wanted to move to R
After transfer, The union worked on both Linux and windows.
However, there was one thing that gave me concern... When copying from E to R, It appears that rclone was cacheing to my NVME C drive, before placing it on one of the other drives Z/X in the union. This obviously brings up questions around unnecessary wear cycle consumption and IO operations.
My understanding is that the VFS cache serves the purpose of allowing you to have full manipulation of the file as if it was a file on the local system. This is handy if the remotes are... well, remote, As the online file storage service may not have the ability to send chunks of the file As needed, or just modify a part of the file with the diff.
I believe however that the rclone union should forego the cashing to the system disc and just do the copy operation directly when all parties involved are local discs for the sake of efficiency, and reduced unnecessary I/O load and flash based storage right cycle consumption.
I know this was asked before in the following help and support thread "Illegal Seek on Local-Only Union", and at the time was stated that "this is a good idea". Windows is lacking an open source union file system handler, with Liquesce development stalling in 2014, and a cross platform solution for disc arrays is sorely lacking. However, it was also mentioned in that thread that there was "not enough bandwidth to implement it!"
I understand if this is still the case. 