Today i was testing out new Windows Server 2019, i did a clean fresh install on a clean drive. After i installed all devices and programs i wanted to test, i powered down my test server. After that I connected a ReFS 3.1 Drive (Windows Server 2016) and without doing anything drive updated to newer 3.4 ReFS that comes with Windows Server 2019. Now this drive is not readable in Windows Server 2016 (Showing as RAW). Drive works perfectly fine on Windows Server 2019 that i used only for testing.
Is there a way to downgrade back to ReFS 3.1 without copying all the data to another disk ? It's a 8TB disk.
ReFS is not intended to be used as a portable format between devices. ReFS version 3.x will automatically promote to the latest format revision supported by the device it is attached. The format revisions are not backward compatible, only forward compatible. So, once a ReFS volume is mounted on a device that supports a later ReFS revision, it will be automatically promoted, and that promotion will render that volume unrecognized on devices that support earlier ReFS revisions. There is no procedure to downgrade the revision, as significant on-disk file system structures have been modified.
So for example I have a server, update windows to server 2019, all ReFS volumes go to latest version, but then I realize that server 2019 has problem with some driver for my device and it is causing a blue screen or whatever, I now have no way to downgrade disk or to go back to server 2016.