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- Btrfs ends up hosing both the outdated and current copies of the mirror, leading to complete dataloss of the entire mirror