From: Avi Kivity <avi@redhat.com>
To: qemu-devel@nongnu.org
Cc: Chris Wright <chrisw@redhat.com>,
Mark McLoughlin <markmc@redhat.com>,
kvm-devel <kvm-devel@lists.sourceforge.net>,
Laurent Vivier <Laurent.Vivier@bull.net>,
Ryan Harper <ryanh@us.ibm.com>, Gerd Hoffmann <kraxel@redhat.com>
Subject: Re: [Qemu-devel] [RFC] Disk integrity in QEMU
Date: Tue, 14 Oct 2008 19:15:21 +0200 [thread overview]
Message-ID: <48F4D3A9.2070207@redhat.com> (raw)
In-Reply-To: <20081012231042.GB22509@shareable.org>
Jamie Lokier wrote:
> However, should the effect of the guest turning off the IDE disk write
> cache perhaps be identical to the guest issuing IDE cache flush commands
> following every IDE write?
>
> This could mean the host calling fdatasync, or fsync, or using
> O_DSYNC, or O_DIRECT - whatever the host does for IDE flush cache.
>
> What this means _exactly_ for data integrity is outside of qemu's
> control and is a user & host configuration issue. But qemu could
> provide consistency at least.
>
We should completely ignore the guest IDE write cache. It was brought
into life by the deficiencies of IDE which presented the user with an
impossible tradeoff -- you can choose between data loss and horrible
performance. Since modern hardware doesn't require this tradeoff, there
is no reason to force the user to make these choices.
--
Do not meddle in the internals of kernels, for they are subtle and quick to panic.
next prev parent reply other threads:[~2008-10-14 17:16 UTC|newest]
Thread overview: 108+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-10-09 17:00 [Qemu-devel] [RFC] Disk integrity in QEMU Anthony Liguori
2008-10-10 7:54 ` Gerd Hoffmann
2008-10-10 8:12 ` Mark McLoughlin
2008-10-12 23:10 ` Jamie Lokier
2008-10-14 17:15 ` Avi Kivity [this message]
2008-10-10 9:32 ` Avi Kivity
2008-10-12 23:00 ` Jamie Lokier
2008-10-10 8:11 ` Aurelien Jarno
2008-10-10 12:26 ` Anthony Liguori
2008-10-10 12:53 ` Paul Brook
2008-10-10 13:55 ` Anthony Liguori
2008-10-10 14:05 ` Paul Brook
2008-10-10 14:19 ` Avi Kivity
2008-10-17 13:14 ` Jens Axboe
2008-10-19 9:13 ` Avi Kivity
2008-10-10 15:48 ` Aurelien Jarno
2008-10-10 9:16 ` Avi Kivity
2008-10-10 9:58 ` Daniel P. Berrange
2008-10-10 10:26 ` Avi Kivity
2008-10-10 12:59 ` Paul Brook
2008-10-10 13:20 ` Avi Kivity
2008-10-10 12:34 ` Anthony Liguori
2008-10-10 12:56 ` Avi Kivity
2008-10-11 9:07 ` andrzej zaborowski
2008-10-11 17:54 ` Mark Wagner
2008-10-11 20:35 ` Anthony Liguori
2008-10-12 0:43 ` Mark Wagner
2008-10-12 1:50 ` Chris Wright
2008-10-12 1:50 ` Chris Wright
2008-10-12 16:22 ` Jamie Lokier
2008-10-12 16:22 ` Jamie Lokier
2008-10-12 17:54 ` Anthony Liguori
2008-10-12 18:14 ` nuitari-qemu
2008-10-13 0:27 ` Mark Wagner
2008-10-13 1:21 ` Anthony Liguori
2008-10-13 2:09 ` Mark Wagner
2008-10-13 3:16 ` Anthony Liguori
2008-10-13 6:42 ` Aurelien Jarno
2008-10-13 14:38 ` Steve Ofsthun
2008-10-12 0:44 ` Chris Wright
2008-10-12 10:21 ` Avi Kivity
2008-10-12 14:37 ` Dor Laor
2008-10-12 14:37 ` Dor Laor
2008-10-12 15:35 ` Jamie Lokier
2008-10-12 18:00 ` Anthony Liguori
2008-10-12 18:02 ` Anthony Liguori
2008-10-12 18:02 ` Anthony Liguori
2008-10-15 10:17 ` Andrea Arcangeli
2008-10-15 10:17 ` Andrea Arcangeli
2008-10-12 17:59 ` Anthony Liguori
2008-10-12 18:34 ` Avi Kivity
2008-10-12 19:33 ` Izik Eidus
2008-10-12 19:33 ` Izik Eidus
2008-10-14 17:08 ` Avi Kivity
2008-10-14 17:08 ` Avi Kivity
2008-10-12 19:59 ` Anthony Liguori
2008-10-12 20:43 ` Avi Kivity
2008-10-12 21:11 ` Anthony Liguori
2008-10-14 15:21 ` Avi Kivity
2008-10-14 15:32 ` Anthony Liguori
2008-10-14 15:43 ` Avi Kivity
2008-10-14 19:25 ` Laurent Vivier
2008-10-16 9:47 ` Avi Kivity
2008-10-12 10:12 ` Avi Kivity
2008-10-17 13:20 ` Jens Axboe
2008-10-19 9:01 ` Avi Kivity
2008-10-19 18:10 ` Jens Axboe
2008-10-19 18:23 ` Avi Kivity
2008-10-19 19:17 ` M. Warner Losh
2008-10-19 19:31 ` Avi Kivity
2008-10-19 18:24 ` Avi Kivity
2008-10-19 18:36 ` Jens Axboe
2008-10-19 19:11 ` Avi Kivity
2008-10-19 19:30 ` Jens Axboe
2008-10-19 20:16 ` Avi Kivity
2008-10-20 14:14 ` Avi Kivity
2008-10-10 10:03 ` Fabrice Bellard
2008-10-13 16:11 ` Laurent Vivier
2008-10-13 16:58 ` Anthony Liguori
2008-10-13 17:36 ` Jamie Lokier
2008-10-13 17:06 ` [Qemu-devel] " Ryan Harper
2008-10-13 18:43 ` Anthony Liguori
2008-10-14 16:42 ` Avi Kivity
2008-10-13 18:51 ` Laurent Vivier
2008-10-13 19:43 ` Ryan Harper
2008-10-13 20:21 ` Laurent Vivier
2008-10-13 21:05 ` Ryan Harper
2008-10-15 13:10 ` Laurent Vivier
2008-10-16 10:24 ` Laurent Vivier
2008-10-16 13:43 ` Anthony Liguori
2008-10-16 16:08 ` Laurent Vivier
2008-10-17 12:48 ` Avi Kivity
2008-10-17 13:17 ` Laurent Vivier
2008-10-14 10:05 ` Kevin Wolf
2008-10-14 14:32 ` Ryan Harper
2008-10-14 16:37 ` Avi Kivity
2008-10-13 19:00 ` Mark Wagner
2008-10-13 19:15 ` Ryan Harper
2008-10-14 16:49 ` Avi Kivity
2008-10-13 17:58 ` [Qemu-devel] " Rik van Riel
2008-10-13 18:22 ` Jamie Lokier
2008-10-13 18:34 ` Rik van Riel
2008-10-14 1:56 ` Jamie Lokier
2008-10-14 2:28 ` nuitari-qemu
2008-10-28 17:34 ` Ian Jackson
2008-10-28 17:45 ` Anthony Liguori
2008-10-28 17:50 ` Ian Jackson
2008-10-28 18:19 ` Jamie Lokier
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=48F4D3A9.2070207@redhat.com \
--to=avi@redhat.com \
--cc=Laurent.Vivier@bull.net \
--cc=chrisw@redhat.com \
--cc=kraxel@redhat.com \
--cc=kvm-devel@lists.sourceforge.net \
--cc=markmc@redhat.com \
--cc=qemu-devel@nongnu.org \
--cc=ryanh@us.ibm.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.