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From: Jamie Lokier <jamie@shareable.org>
To: qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [RFC][PATCH] make sure disk writes actually hit disk
Date: Sun, 30 Jul 2006 22:47:12 +0100	[thread overview]
Message-ID: <20060730214712.GB6255@mail.shareable.org> (raw)
In-Reply-To: <23bcb8700607291033q7ce66872j2ce2d830a8578dbc@mail.gmail.com>

Bill C. Riemers wrote:
>    How  about  compromising,  and  making  the  patch  a run time option.
>    Presumably  this  is  only  a  problem when the virtual machine is not
>    properly  shutdown.   For  those ho want the extra security of knowing
>    the  data  will  be written regardless of the shutdown status they can
>    enable  the  flag.  By default it could be turned off.  Then everybody
>    can be happy.

Real disks don't provide that security unless you disable the disk's
cache, or issue cache flush instructions to the disk.

Modern guest OS filesystems are written with this in mind.

With older guest OSes, you have to disable the disk cache if you want
that kind of security with real disks.

Is there any reason why the emulation should be any different?

-- Jamie

  reply	other threads:[~2006-07-30 21:47 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-07-28 19:54 [Qemu-devel] [RFC][PATCH] make sure disk writes actually hit disk Rik van Riel
2006-07-28 19:58 ` [Qemu-devel] " Rik van Riel
2006-07-28 20:12 ` Anthony Liguori
2006-07-28 20:18   ` Rik van Riel
2006-07-28 20:30     ` Paul Brook
2006-07-28 20:43       ` Rik van Riel
2006-07-28 21:01         ` Paul Brook
2006-07-31  7:08     ` Jens Axboe
2006-07-29  9:57 ` [Qemu-devel] " Fabrice Bellard
2006-07-29 14:59   ` Rik van Riel
2006-07-29 16:04     ` Paul Brook
2006-07-29 16:22       ` Rik van Riel
2006-07-29 16:31         ` Paul Brook
2006-07-31  7:08           ` Jens Axboe
2006-07-29 17:33     ` Bill C. Riemers
2006-07-30 21:47       ` Jamie Lokier [this message]
2006-07-30 21:41     ` Jamie Lokier
2006-07-31  9:52       ` andrzej zaborowski
2006-07-31 10:17         ` Jens Axboe
2006-07-31 17:50           ` andrzej zaborowski
2006-07-31  7:08     ` Jens Axboe
2006-07-31  7:56       ` Jonas Maebe
2006-07-31  8:18         ` Jens Axboe

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