[rleigh]

There are still major bugs in the rest of it. You can trivially corrupt a mirror. There are examples for how to reproduce it exactly in qemu with virtual drives. I caused me total dataloss on my first Btrfs filesystem at least 8 years back. That bug is apparently still there. The unbalancing issues are still there. I have zero trust of Btrfs in any form.

[leetnewb]

Can you link to that? I have been using btrfs in raid1 and single for ~3-4 years now without any data loss.

[rleigh]

You (and many others) might well be using RAID1 mirrors without problems. I did as well. But the problems here are not encountered during day-to-day usage. They are bugs in the recovery codepaths following hardware failures. I suffered this due to a transient SATA cable glitch, but the instructions let you exactly reproduce this with qemu with a recent kernel. I've not tried the qemu approach myself; I moved over to ZFS a good while back now.

I've had a hunt for the specific instructions but I'm afraid I can't find it again with a search. The gist of it was to:

- create Btrfs mirror using two qemu virtual disks

- pull the (virtual) plug on one of the pair to disconnect it, then later reconnect it

- Btrfs ends up hosing both the outdated and current copies of the mirror, leading to complete dataloss of the entire mirror