From: Roman Mamedov <rm@romanrm.net>
To: Zygo Blaxell <ce3g8jdj@umail.furryterror.org>
Cc: 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: Thu, 13 Oct 2016 00:33:31 +0500 [thread overview]
Message-ID: <20161013003331.5e33c006@natsu> (raw)
In-Reply-To: <20161012191915.GF26140@hungrycats.org>
[-- Attachment #1: Type: text/plain, Size: 1066 bytes --]
On Wed, 12 Oct 2016 15:19:16 -0400
Zygo Blaxell <ce3g8jdj@umail.furryterror.org> wrote:
> I'm not even sure btrfs does this--I haven't checked precisely what
> it does in dup mode. It could send both copies of metadata to the
> disks with a single barrier to separate both metadata updates from
> the superblock updates. That would be bad in this particular case.
It would be bad in any case, including a single physical disk and no RAID, and
I don't think there's any basis to speculate that mdadm doesn't implement
write barriers properly.
> In degraded RAID5/6 mode, all writes temporarily corrupt data, so if there
> is an interruption (system crash, a disk times out, etc) in degraded mode,
Moreover, in any non-COW system writes temporarily corrupt data. So again,
writing to a (degraded or not) mdadm RAID5 is not much different than writing
to a single physical disk. However I believe in the Btrfs case metadata is
always COW, so this particular problem may be not as relevant here in the
first place.
--
With respect,
Roman
[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 181 bytes --]
next prev parent reply other threads:[~2016-10-12 19:35 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
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 [this message]
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20161013003331.5e33c006@natsu \
--to=rm@romanrm.net \
--cc=ahferroin7@gmail.com \
--cc=ce3g8jdj@umail.furryterror.org \
--cc=hugo@carfax.org.uk \
--cc=linux-btrfs@vger.kernel.org \
--cc=lists@colorremedies.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.