On Thu, Nov 16, 2017 at 6:22 PM, Qu Wenruo <quwenruo.btrfs@xxxxxxx> wrote: > > > On 2017年11月17日 06:32, Chris Murphy wrote: > >> It's good the file system can stay alive, but data is the much >> bigger target in terms of percent space on the physical media, > > It's also true. > (Although working on btrfs sometimes makes me care more about safe metadata) It seems like a good idea if it's lightweight enough, because we get Btrfs-like metadata error detection and recovery from a copy, for free. The user doesn't have to setup dm-verity to get this. Additionally, if the work happens in the md driver, then both mdadm and LVM based arrays get the feature (strictly speaking I think dm-raid is deprecated, everything I'm aware of these days uses the md code (including Intel's IMSM firmware based RAID). The gotcha of course is that anytime there's a file system format change, now this layer has to become aware of it and support all versions of that file system's metadata for the purpose of error detection. That might be a bitter pill to swallow in the long term. -- Chris Murphy
