From: Chris Murphy <lists@colorremedies.com>
To: Zygo Blaxell <ce3g8jdj@umail.furryterror.org>
Cc: Qu Wenruo <quwenruo@cn.fujitsu.com>,
Chris Murphy <lists@colorremedies.com>,
Hugo Mills <hugo@carfax.org.uk>,
"linux-btrfs@vger.kernel.org" <linux-btrfs@vger.kernel.org>,
Austin Hemmelgarn <ahferroin7@gmail.com>
Subject: Re: RAID system with adaption to changed number of disks
Date: Wed, 12 Oct 2016 14:41:56 -0600 [thread overview]
Message-ID: <CAJCQCtSrG+2AudyPjgfqZw0FbJkGNdN3UN6pdSmAx7+G4FD32w@mail.gmail.com> (raw)
In-Reply-To: <20161012171936.GD26140@hungrycats.org>
On Wed, Oct 12, 2016 at 11:19 AM, Zygo Blaxell
<ce3g8jdj@umail.furryterror.org> wrote:
> Degraded RAID5 is not RAID0. RAID5 has strict constraints that RAID0
> does not. The way a RAID5 implementation behaves in degraded mode is
> the thing that usually matters after a disk fails.
Is there degraded raid5 xfstesting happening? Or are the tests mainly
done non-degraded? In particular, 2x device fail degraded raid6,
because it's so expensive, has potential to expose even more bugs.
> So...metadata blocks would be 256K on the 5-disk RAID5 example above,
> and any file smaller than 256K would be stored inline? Ouch. That would
> also imply the compressed extent size limit (currently 128K) has to become
> much larger.
There are patches to set strip size. Does it make sense to specify
4KiB strip size for metadata block groups and 64+KiB for data block
groups?
--
Chris Murphy
next prev parent reply other threads:[~2016-10-12 20:49 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-11 15:14 RAID system with adaption to changed number of disks Philip Louis Moetteli
2016-10-11 16:06 ` Hugo Mills
2016-10-11 23:58 ` Chris Murphy
2016-10-12 1:32 ` Qu Wenruo
2016-10-12 4:37 ` Zygo Blaxell
2016-10-12 5:48 ` Qu Wenruo
2016-10-12 17:19 ` Zygo Blaxell
2016-10-12 19:55 ` Adam Borowski
2016-10-12 21:10 ` Zygo Blaxell
2016-10-13 3:40 ` Adam Borowski
2016-10-12 20:41 ` Chris Murphy [this message]
2016-10-13 0:35 ` Qu Wenruo
2016-10-13 21:03 ` Zygo Blaxell
2016-10-14 1:24 ` Qu Wenruo
2016-10-14 7:16 ` Chris Murphy
2016-10-14 19:55 ` Zygo Blaxell
2016-10-14 21:19 ` Duncan
2016-10-14 21:38 ` Chris Murphy
2016-10-14 22:30 ` Chris Murphy
2016-10-15 3:19 ` Zygo Blaxell
2016-10-12 7:02 ` Anand Jain
2016-10-12 7:25 ` Roman Mamedov
2016-10-12 17:31 ` Zygo Blaxell
2016-10-12 19:19 ` Zygo Blaxell
2016-10-12 19:33 ` Roman Mamedov
2016-10-12 20:33 ` Zygo Blaxell
2016-10-11 16:37 ` Austin S. Hemmelgarn
2016-10-11 17:16 ` Tomasz Kusmierz
2016-10-11 17:29 ` ronnie sahlberg
2016-10-12 1:33 ` Dan Mons
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