btrfs on top of an mdadm array with RAID6 is not an option. In this case btrfs sees only the one device, e.g. /dev/md127, which would make all the redundancy handling in btrfs obsolete. mdadm would have to do all the checking and scrubing which would basically make btrfs useless except for the snapshot functionality.
So when will btrfs support RAID6? I was searching for roadmap information, delevoper notes on the topic etc. But could not find anything. Are the btrfs developers working on this topic at all?
If you have an adequate spare system, perhaps you could coordinate development with them. But the EnOS team has nothing to do with the BTRFS roadmap, you could probably have asked on some BTRFS forum or smth.
(It seems like it’s on hold, maybe ZFS or smth if you need RAID6)
My intention is not to participate in btrfs development. I am just a linux user seeking information about the btrfs roadmap resp. bug fixing status.
I am well aware that Endeavouros has nothing to do with btrfs development. But this forum has some very knowledgeable members which are much closer to kernel development, which have much more knowledge about btrfs and which eventually know a source of information which I have not found yet.
As I explained right at the beginning of my initial post I am using zfs with RAIDZ2 since several years.
In the meantime I digged more into this topic and I got an answer from one of the btrfs developers. He pointed me to a new function called ‘raid stripe tree’ which was introduced with kernel 6.7.
The commit says:
Introduce the RAID stripe tree, a new tree for logical file extent mapping where the physical mapping may not match on multiple devices. This is now used in zoned mode to implement RAID0/RAID1* profiles, but can be used in non-zoned mode as well. The support for RAID56 is in development and will eventually fix the problems with the current implementation. This is a backward incompatible feature and has to be enabled at mkfs time
Newer kernels did not receive any update to ‘raid stripe tree’. Which means that there is still no progress with regard to RAID56. But at least there is more hope now.
People have been waiting for stabke raid 5/6 support in btrfs for years now. I think it is a long ways off before we see a truly stable and reliable implementation