Parity is just if you’re running raidz, and the only tuning is if it’s 1 2 or 3 drive loss tolerances.
CoW is on or off.
Checksums, I don’t think you can turn off.
ZIL is definitely something you can tune, but you can also set up a SLOG device (separate log) for this, to improve your overall performance.
Same here. I hate facebook, but you can’t deny that their compression algorithm is the best out there. Arch compresses all their packages with zstd now.
datasets are like thin-provisioned filesystems.
Think of it as a folder, but it has tunable filesystem properties and ZFS can administer it. You should have a dataset for each distinct category of data. I can give you more details if you want.
Used to be 4TB, but it might be going up now. I’d check /r/datahoarder for best results.
It’s worth noting that BTRFS is a worthy contender if you use raid10 instead of parity. (their parity implementation is broken and the write hole still exists, IIRC)
BTRFS has the benefit of being flexible, but ZFS is working on flexibility soon, I think, with device removal or raidz resizing.