Mergerfs + snapraid

If a drive fails, you only need the parity disk to restore, not the whole array. Also, if for some reason you can’t restore, you only lose data on the failed drive.

ZFS is great and for real NAS data, I’m a fan. But for large media files and and such that you are write once, read many, it’s a much better option I think.

Mergerfs is just to present all 20 drives as a single mount point so you aren’t searching thru 20 drives when you want to view.

I’ve been on mergerfs + snapraid for years and haven’t had any issues. I even tried downloading to a NVMe but then you just move the bottleneck from downloading to moving off the cache drive. And if you download more than your cache drive, you’re no better off.

Setup mergerfs and make sure and specify “most free space”. Then each file will actually get written to a different drive because it evaluates the space and rotates the writes. The n just run snapraid nightly to keep parity in sync. (This does mean you could lose something between download and sync, but if you just downloaded, you can probably grab again)

Now, the big assumption here is that most of your files are large media files. If you’re moving thousands of small files, you’ll probably notice a performance hit.

I can easily saturate my 2.5 gbps fiber connection with no issues. And as others have said, it’s just standard files and you’re not hosed it a single drive dies.