I used to run a manual version of mergerfs (before it existed) - a bunch of disks, files were manually copied into one of the disks, and scripts maintained "tre

I used to run a manual version of mergerfs (before it existed) - a bunch of disks, files were manually copied into one of the disks, and scripts maintained "tree of symlinks" which pointed to all the files. Later on, I needed to export this as SMB, so I've added de-referencing overlayfs to generate a single huge disk, and exported that. Worked pretty well and while manual placing required some effort, I could keep similar files together. Later on I ended up buying few more disks and creating large ZFS RAID6 array.. And it "just works" now, no need for custom scripts.