[vishnu]

Copy-on-Write is a very specific filesystem setup not suited for low memory infrastructure or plain, just really ugly and complex. It doesn't have some of the raw single disk performance of a traditional FS, and while checksums are fine in COW (because snapshots) if none of that is set up, e.g. for a user that just wants something that "works" or that lacks the memory and background resources, checksumming on a normal filesystem is just a plain annoyance.

COW systems are not my personal thing anymore. It's a meme, a pseudo-killer app but we didn't need it for nearly 40 years prior, so we probably don't need it now.

Again, I respectfully have to disagree. When I was at Northern Telecom, and we were marketing massively expensive private branch exchanges to, more or less, huge corporates, where the dropping of a call was absolutely not, well, we just couldn't allow it. We wrote test suites up that we ran for weeks, including ROM checksums (back in those days the systems didn't contain any RAM), and prior to that, when I worked at AT&T they were doing the same thing (though I wasn't programming the checksum code). But seriously, I don't know anything about BSD, are you saying they DON'T use copy on write? I mean, in my opinion, and other opinions will no doubt vary, what is the point in NOT using copy on write? It conserves memory it doesn't abuse it! Well, whatever, maybe I don't know what I'm talking about anymore, I haven't written any copy on write code since the 80s.