> I have an irrational fear of data loss, and ext4 has never failed me
You're a lot more likely to lose/corrupt data with ext4 than ZFS. Ext4 will happily corrupt data silently. The core conceit of ZFS is it doesn't trust the underlying hardware. ZFS even allows duplicated data on a single disk. You lose capacity but gain robustness.
Like I said, I've used ext* filesystems for decades now, and have yet to experience corruption or data loss. I know ZFS would detect and correct or notify this automatically, but this can be avoided with ext4 by doing frequent backups, and using tools like SnapRAID or par2. Sure, this needs to be done manually, but for my use cases this works rather well, and I enjoy the flexibility and direct control over this, rather than using a complex/magic file system that does this transparently for me.
When ZFS support in Linux was still new, I wouldn't dare rely on it, and it's the same reason I avoid btrfs today, even though its features are appealing. But now that ZFS is quite stable, and after hearing its praises for years, I do want to give it a try. :)
> this can be avoided with ext4 by doing frequent backups
lol. Nothing is stopping you from doing manual backups using ZFS. One should never rely on just one backup anyways, if the data is critical. For me, snapshots are a great way to protect from "oh, I accidentally deleted this folder", which ext4 doesn't have. Yes, you can use replication to sync these snapshots somewhere else, but nothing is stopping you from continuing to do manual backups on a file level. It's just a file system, after all. So it doesn't really make sense as a justification as to why you are hesitant to use ZFS. In fact, it's one of the reasons I liked it so much: While you can do all these cool things with it, you don't have to. It doesn't pressure you to use these features. If you're ready, they're there, but until then, it's just a file system, and a very robust one at that.
> I've used ext* filesystems for decades now, and have yet to experience corruption or data loss
You might not know. How are you validating the integrity of every file regularly?
In the 90s I lost some files to corruption which went unnoticed for years and propagated to every backup, so by the time I went looking for the file I had years worth of backups of those files, all corrupt. This is one of the reasons zfs is such a happy place.
I get that. But in practice, it hasn't been a problem. For files I consider critical and difficult to replace, I use SnapRAID or par2, and others are either used frequently and I would notice the corruption, or replacing them wouldn't be a problem.
Using a smart filesystem would be an improvement, but it comes at the expense of less flexibility and more complexity, and, until recently on Linux at least, relying on unstable software.
Where the hell are you getting this from? What instability has existed in ZFS on Linux? Are you confusing it with BTRFS or something? I think your fears of ZFS are seriously misplaced.
You're a lot more likely to lose/corrupt data with ext4 than ZFS. Ext4 will happily corrupt data silently. The core conceit of ZFS is it doesn't trust the underlying hardware. ZFS even allows duplicated data on a single disk. You lose capacity but gain robustness.