On Fri, Jul 26, 2019 at 07:41:41AM +0800, Qu Wenruo wrote: > > > On 2019/7/26 上午2:37, David Sterba wrote: > > On Thu, Jul 18, 2019 at 02:27:49PM +0800, Qu Wenruo wrote: > >> RAID10 can accept as much as half of its disks to be missing, as long as > >> each sub stripe still has a good mirror. > > > > Can you please make a test case for that? > > Fstests one or btrfs-progs one?
For fstests. > > I think the number of devices that can be lost can be higher than a half > > in some extreme cases: one device has copies of all stripes, 2nd copy > > can be scattered randomly on the other devices, but that's highly > > unlikely to happen. > > > > On average it's same as raid1, but the more exact check can potentially > > utilize the stripe layout. > > > That will be at extent level, to me it's an internal level violation, > far from what we want to improve. Ah I don't mean to go the extent level, as you implemented it is enough and an improvement.
