On Thu, Sep 11, 2014 at 08:06:21AM -0400, Austin S Hemmelgarn wrote: > On 2014-09-11 07:38, Hugo Mills wrote: > > On Thu, Sep 11, 2014 at 07:19:00AM -0400, Austin S Hemmelgarn wrote: > >> On 2014-09-11 02:40, Russell Coker wrote: > >>> Also it would be nice if there was a N-way mirror option for system data. > >>> As > >>> such data is tiny (32MB on the 120G filesystem in my workstation) the > >>> space > >>> used by having a copy on every disk in the array shouldn't matter. > >> > >> N-way mirroring is in the queue for after RAID5/6 work; ideally, once it > >> is ready, mkfs should default to one copy per disk in the filesystem. > > > > Why change the default from 2-copies, which it's been for years? > > Sorry about the ambiguity in my statement, I meant that the default for > system chunks should be one copy per disk in the filesystem. If you > don't have a copy of the system chunks, then you essentially don't have > a filesystem, and that means that BTRFS RAID6 can't provide true > resilience against 2 disks failing catastrophically unless there are at > least 3 copies of the system chunks.
Aah, OK. That makes perfect sense, then. Hugo. -- === Hugo Mills: hugo@... carfax.org.uk | darksatanic.net | lug.org.uk === PGP key: 65E74AC0 from wwwkeys.eu.pgp.net or http://www.carfax.org.uk --- Some days, it's just not worth gnawing through the straps ---
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