All of lore.kernel.org
 help / color / mirror / Atom feed
From: Marc Bevand <m.bevand@gmail.com>
To: Jamie Lokier <jamie@shareable.org>
Cc: qemu-devel@nongnu.org, Gleb Natapov <gleb@redhat.com>,
	kvm@vger.kernel.org
Subject: Re: [Qemu-devel] Re: qcow2 corruption observed, fixed by reverting old change
Date: Fri, 13 Feb 2009 22:31:29 -0800	[thread overview]
Message-ID: <aaccfcb60902132231v53b54070sf7a0151ee565214@mail.gmail.com> (raw)
In-Reply-To: <20090213162336.GI18471@shareable.org>

On Fri, Feb 13, 2009 at 8:23 AM, Jamie Lokier <jamie@shareable.org> wrote:
>
> Marc..  this is quite a serious bug you've reported.  Is there a
> reason you didn't report it earlier?

Because I only started hitting that bug a couple weeks ago after
having upgraded to a buggy kvm version.

> Is there a way to restructure the code and/or how it works so it's
> more clearly correct?

I am seriously concerned about the general design of qcow2. The code
base is more complex than it needs to be, the format itself is
susceptible to race conditions causing cluster leaks when updating
some internal datastructures, it gets easily fragmented, etc.

I am considering implementing a new disk image format that supports
base images, snapshots (of the guest state), clones (of the disk
content); that has a radically simpler design & code base; that is
always consistent "on disk"; that is friendly to delta diffing (ie.
space-efficient when used with ZFS snapshots or rsync); and that makes
use of checksumming & replication to detect & fix corruption of
critical data structures (ideally this should be implemented by the
filesystem, unfortunately ZFS is not available everywhere :D).

I believe the key to achieve these (seemingly utopian) goals is to
represent a disk "image" as a set of sparse files, 1 per
snapshot/clone.

-marc

  parent reply	other threads:[~2009-02-14  6:31 UTC|newest]

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-02-11  7:00 qcow2 corruption observed, fixed by reverting old change Jamie Lokier
2009-02-11  7:00 ` [Qemu-devel] " Jamie Lokier
2009-02-11  9:57 ` Kevin Wolf
2009-02-11 11:27   ` Jamie Lokier
2009-02-11 11:27     ` Jamie Lokier
2009-02-11 11:41   ` Jamie Lokier
2009-02-11 11:41     ` Jamie Lokier
2009-02-11 12:41     ` Kevin Wolf
2009-02-11 12:41       ` Kevin Wolf
2009-02-11 16:48       ` Jamie Lokier
2009-02-11 16:48         ` Jamie Lokier
2009-02-12 22:57         ` Consul
2009-02-12 22:57           ` [Qemu-devel] " Consul
2009-02-12 23:19           ` Consul
2009-02-12 23:19             ` [Qemu-devel] " Consul
2009-02-13  7:50             ` Marc Bevand
2009-02-16 12:44         ` [Qemu-devel] " Kevin Wolf
2009-02-17  0:43           ` Jamie Lokier
2009-02-17  0:43             ` Jamie Lokier
2009-03-06 22:37         ` Filip Navara
2009-03-06 22:37           ` Filip Navara
2009-02-12  5:45       ` Chris Wright
2009-02-12  5:45         ` Chris Wright
2009-02-12 11:08         ` Johannes Schindelin
2009-02-12 11:08           ` Johannes Schindelin
2009-02-13  6:41 ` Marc Bevand
2009-02-13 11:16   ` Kevin Wolf
2009-02-13 11:16     ` [Qemu-devel] " Kevin Wolf
2009-02-13 16:23     ` Jamie Lokier
2009-02-13 16:23       ` Jamie Lokier
2009-02-13 18:43       ` Chris Wright
2009-02-13 18:43         ` Chris Wright
2009-02-14  6:31       ` Marc Bevand [this message]
2009-02-14 22:28         ` Dor Laor
2009-02-14 22:28           ` Dor Laor
2009-02-15  2:27           ` Jamie Lokier
2009-02-15  7:56           ` Marc Bevand
2009-02-15  7:56             ` Marc Bevand
2009-02-15  2:37         ` Jamie Lokier
2009-02-15 10:57     ` Gleb Natapov
2009-02-15 10:57       ` [Qemu-devel] " Gleb Natapov
2009-02-15 11:46       ` Marc Bevand
2009-02-15 11:46         ` [Qemu-devel] " Marc Bevand
2009-02-15 11:54         ` Marc Bevand
2009-02-15 11:54           ` [Qemu-devel] " Marc Bevand

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=aaccfcb60902132231v53b54070sf7a0151ee565214@mail.gmail.com \
    --to=m.bevand@gmail.com \
    --cc=gleb@redhat.com \
    --cc=jamie@shareable.org \
    --cc=kvm@vger.kernel.org \
    --cc=qemu-devel@nongnu.org \
    /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.