Here is another different kind of setup which triggers the problem:
/boot ext4 on a md RAID10 (4 HDD) partition
/ btrfs RAID10 (4 HDD) partition
swap on a md RAID0 (4HDD) partition
The boot and kernel are on a MD RAID (software RAID), whereas the rest of the system is using Btrfs RAID.
Here is another different kind of setup which triggers the problem:
/boot ext4 on a md RAID10 (4 HDD) partition
/ btrfs RAID10 (4 HDD) partition
swap on a md RAID0 (4HDD) partition
The boot and kernel are on a MD RAID (software RAID), whereas the rest of the system is using Btrfs RAID.