On Fri, Jan 18, 2019 at 12:02 AM Stefan K <shadow_7@xxxxxxx> wrote: > > > Btrfs raid10 really should not be called raid10. It sets up the wrong > > user expectation entirely. It's more like raid0+1, except even that is > > deceptive because in theory a legit raid0+1 you can lose multiple > > drives on one side of the mirror (but not both); but with Btrfs raid10 > > you really can't lose more than one drive. And therefore it does not > > scale. The probability of downtime increases as drives are added; > > whereas with a real raid10 downtime doesn't change. > WTF?! really, so with btrfs raid10 I can't lose more than one drive? Correct. >that sucks, that an advantage of raid 10! > and the crazy thing is, thats not documented, not in the manpage nor btrfs wiki and and thats is very important. > thats unbelievable .. Yep. It comes up from time to time, it's discussed in the archives. I suspect if someone comes up with a btrfs-progs patch to add a warning note under the block group profiles grid (note 4 perhaps) I suspect it'd get accepted. -- Chris Murphy
