SnapRAID + MergerFS for a home NAS
A popular alternative to traditional RAID for home media servers: MergerFS pools multiple independent drives into one folder tree, while SnapRAID adds parity protection you can add drives to (or recover from) one at a time.
1Install both tools
sudo apt updatesudo apt install -y snapraid mergerfs2Pool your drives with MergerFS
Mount several independently-formatted drives as one combined folder -- files are distributed across the underlying drives, but appear in a single unified directory tree.
sudo mkdir -p /mnt/disk1 /mnt/disk2 /mnt/parity /mnt/storagesudo mergerfs /mnt/disk1:/mnt/disk2 /mnt/storage -o defaults,allow_other,use_ino,category.create=mfs3Configure SnapRAID parity protection
Edit /etc/snapraid.conf to list each data drive and a separate parity drive (which must be at least as large as your biggest data drive), then run an initial sync.
sudo snapraid syncUnlike RAID, SnapRAID parity is NOT real-time -- it only protects data as of your last `snapraid sync` run, so schedule that as a regular cron job, and know that anything changed since the last sync isn't protected yet.
4Recover from a failed drive
If one data drive fails, SnapRAID can rebuild its exact contents onto a replacement drive using the parity data and the other drives -- your other drives are completely unaffected and don't need to be touched.