This would mean that zfs is also "traditional raid" since the math behind raid 5/raidz1 (https://blogs.oracle.com/solaris/post/understanding-raid-5-recovery-with-elementary-school-math
) and raid 6/raidz2 (https://blogs.oracle.com/solaris/post/understanding-raid-6-with-junior-high-math
) is the same. (Both blog posts are from a zfs developer from oracle)
"In a way that's more or less the same", using the same parity math isn't where an issue would be (unless that parity math is flawed). And I will note that blog doesn't go over the *actual* math, but I think that's sort of a tangent to this anyways.
RaidZ doesn't have the same write-hole that most hardware/software raids do.
RaidZ isn't logically separated from the file system, while you can create a virtual block device touse any file system you want that's an abstraction and ZFS is still "under" that.
RaidZ rebuilds (resilver) only care about data (since it's linked to the file system, that awareness exists)
RaidZ doesn't lay out blocks on the disk in the same way (the exact difference is something I'd need to refresh my memory)
But, IMHO, the biggest difference is RaidZ/ZFS has a lower level of "trust" of the hardware, this is at the ZFS layer so even single disk setups have some protection. RAID with parity is *supposed* to have that, but many solutions silently *don't*.
Granted, these differences come with large tradeoffs in performance, hardware considerations, limitation to a single "native" file system, etc.
There *are* raid solutions out there that still work the way people believe they do, but you need the right disks and the right hardware/software solution or you could very easily have little or no additional protection VS a single disk. And in all cases, RAID is not a backup (nor RaidZ). It's at least a *little* easier to test Raid than it is to test ECC memory (write directly to a member disk, from another computer if you need to, test what happens when you read)
Relating to this thread, MooseFS is actually acting a bit like ZFS here (broadly speaking), maintaining checksums on files and claims to do re-reads from other copies if needed. Assuming MooseFS does what it says well, it would (IMHO) make raid5/6 more useful since it would solve at least some data integrity issues. What I don't know is if MooseFS can "rebuild" a file (say from two partially correct sources) or if it's just a checksum/hash/