Now that the poll has ended, I'm not surprised by the results at all. It's not exactly what I would have predicted (I'd have thought ext4 would win over btrfs, if only just slightly), but very close!

I have had my opinions on bcachefs and btrfs. There's no way I'll ever use bcachefs if the choice is up to me, waay too many rough edges, and from what I've seen, they aren't handled too well.

I did not have much of an opinion on xfs or ext4: I've read many praises of XFS being boring but stable, and boring and stable is great. But I've been using ext* since the dawn of time. The only time I had problems is when my disks had problems, replaced them, restored from backups, all was well. As such, I don't see XFS offering me much, apart from being, well, not ext4.

I did not have a high opinion on btrfs, either. It too, had a rough start, and for a long time, my impression was that it's a "future filesystem forever". High ambitions that'll never be reached. As far as I understand, it still has rough edges in various cases.

For what I'm going to use the server for, I do not fall into those cases. I just want a system where I can use multiple devices to make up a single filesystem, one that is able to store at most two snapshots. I don't need a raid, I don't need anything very fancy. Just a bigass filesystem that I can grow (I'm not going to shrink it, ever), one I can encrypt. That's it.

LUKS+LVM+ext4 gets that for me, and so does LUKS+BTRFS.

What can BTRFS offer me that ext4 can't? Something that would be useful to me?

I don't care much about inodes (I ran out of inodes a few times, on small servers, when I made the partition too small - that's not going to be a problem on the new server), I like data & metadata checksumming, but I lived without that for a long time. I have monitoring and backups. Snapshots? LVM can do that, too. Might be less efficient, might be slow if I store more than a handful of snapshots - but I don't. I don't plan to use more than two, if even that.

Subvolumes I don't see a use for (yes, I know, snapshots. You can do snapshots without subvolumes, so this is a technical detail I care little about).

It can do compression, though, and I expect there to be a number of well compressable files, so this at least sounds interesting.

Now... do I change the trusty LVM+ext4 combo that worked for the past 20 years to BTRFS, a system I haven't even experimented with?

Yeah, yeah I will. While this is a server I'm putting into production, it is my server. This feels like a good time to play with something new, and BTRFS won't be the only new thing I'm playing with, so, why not? When else would I learn, under realistic circumstances?

If it fails me, the server will be in my room, on the shelf. I'll just re-deploy the operating system with LUKS+LVM+ext4, and restore persistent data from backups. I'll change it out in a heartbeat if I need to, and I can do that in a few hours (re-deploying the OS is about 5 minutes, restoring from backups will take by far the longest).