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Date: Sun, 23 Mar 2014 22:52:29 +0000
From: Hugo Mills <hugo@carfax.org.uk>
To: Marc MERLIN <marc@merlins.org>
Cc: linux-btrfs@vger.kernel.org
Subject: Re: Any use for mkfs.btrfs -d raid5 -m raid1 ?
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On Sun, Mar 23, 2014 at 03:44:35PM -0700, Marc MERLIN wrote:
> If I lose 2 drives on a raid5, -m raid1 should ensure I haven't lost my
> metadate.
> From there, would I indeed have small files that would be stored entirely=
 on
> some of the drives that didn't go missing, and therefore I could recover
> some data with 2 missing drives?

   btrfs's RAID-1 is two copies only, so you may well have lost some
of your metadata. n-copies RAID-1 is coming Real Soon Now=E2=84=A2 (Chris h=
as
it on his todo list, along with fixing all the parity RAID stuff).

> Or is it kind of pointless/waste of space?
>=20
> Actually, would it make btrfs faster for metadata work since it can read
> from n drives in parallel and get data just a bit faster, or is that most=
ly
> negligeable?

   I don't think we've got good benchmarks from anyone on any of this
kind of thing.

   Hugo.

--=20
=3D=3D=3D Hugo Mills: hugo@... carfax.org.uk | darksatanic.net | lug.org.uk=
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