On Thu, Apr 2, 2020 at 5:09 AM Filipe Manana <fdmanana@xxxxxxxxx> wrote: > > Any thoughts? Perhaps someone else was already aware of this problem and > had thought about this before. Josef? Upon degraded, there is some data that is only ever written as P or Q. This requires two stripe elements to successfully be read to reconstruct what is missing (because it was tossed, because of the degraded state). What about falling back to raid1 (for raid5) or raid1c3 (for raid6)? That is, freeze the raid56 metadata block groups, and only do new writes to raid1 or raid1c3? Alternatively, disallow raid56 for metadata going forward. Make it not possible to use -mraid5 or -mraid6 at mkfs time. And explicitly recommend everyone convert. This might be the easiest fix. -- Chris Murphy
