I am currently using MergerFS to crerate a single logical volume over my two physical HDDs. Coincidentally, my drives happen to use BTFRS. From what i read i understand that BTFRS already supports drive pooling and no need to use union file systems tools like mergerfs. However, this BTFRS drive pooling does not seem to be supported by the OMV GUI. MergerFS works fine, but has quite a performance overhead where my old HP microserver is struggling a bit, so i'd rather use something supported directly by kernel instead of FUSE.
So the question is: is a data migration like that supported in OMV and can be done without data loss on the existing drives?