On Mon, Dec 18, 2017 at 3:28 PM, Chris Murphy <lists@xxxxxxxxxxxxxxxxx> wrote: > On Mon, Dec 18, 2017 at 1:49 AM, Anand Jain <anand.jain@xxxxxxxxxx> wrote: > >> Agreed. IMO degraded-raid1-single-chunk is an accidental feature >> caused by [1], which we should revert back, since.. >> - balance (to raid1 chunk) may fail if FS is near full >> - recovery (to raid1 chunk) will take more writes as compared >> to recovery under degraded raid1 chunks > > > The advantage of writing single chunks when degraded, is in the case > where a missing device returns (is readded, intact). Catching up that > device with the first drive, is a manual but simple invocation of > 'btrfs balance start -dconvert=raid1,soft -mconvert=raid1,soft' The > alternative is a full balance or full scrub. It's pretty tedious for > big arrays. > > mdadm uses bitmap=internal for any array larger than 100GB for this > reason, avoiding full resync. > > 'btrfs sub find' will list all *added* files since an arbitrarily > specified generation; but not deletions. Looks like LVM raid types (the non-legacy ones that use md driver) also use a bitmap by default. -- Chris Murphy -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
