All of lore.kernel.org
 help / color / mirror / Atom feed
From: Anthony Liguori <anthony@codemonkey.ws>
To: Kevin Wolf <kwolf@redhat.com>
Cc: "Daniel P. Berrange" <berrange@redhat.com>,
	Chris Wright <chrisw@redhat.com>, kvm-devel <kvm@vger.kernel.org>,
	armbru@redhat.com, qemu-devel@nongnu.org,
	Luiz Capitulino <lcapitulino@redhat.com>
Subject: Re: [Qemu-devel] Re: KVM call minutes for June 8
Date: Thu, 10 Jun 2010 09:27:34 -0500	[thread overview]
Message-ID: <4C10F656.20305@codemonkey.ws> (raw)
In-Reply-To: <4C10E3B2.9070905@redhat.com>

On 06/10/2010 08:08 AM, Kevin Wolf wrote:
> Am 10.06.2010 14:53, schrieb Anthony Liguori:
>    
>> On 06/10/2010 04:43 AM, Kevin Wolf wrote:
>>      
>>> Huh, why this? Seems I still haven't understood all of qcow2 then... I
>>> always thought that there's just a specific offset where VM state
>>> starts, but no explicit end.
>>>
>>>        
>> A live snapshot can last for a very long time.  What happens if you need
>> to allocate a new block for disk I/O while saving a snapshot?
>>      
> You allocate it, I guess?
>
> Note that VM state must be virtually contiguous, but not necessarily
> physically (virtually = on the virtual hard disk as seen by the guest;
> physically = in the image file). It's just not seen by the guest because
> it's saved at a high offset that is after the end of the real disk
> content, but otherwise it should behave the same as guest data.
>    

I guess you could just start writing and then once your finished, you 
could update the snapshot information.  So yeah, I think your right that 
it's doable with the current format.

Regards,

Anthony Liguori

> Kevin
>    


WARNING: multiple messages have this Message-ID (diff)
From: Anthony Liguori <anthony@codemonkey.ws>
To: Kevin Wolf <kwolf@redhat.com>
Cc: Chris Wright <chrisw@redhat.com>, kvm-devel <kvm@vger.kernel.org>,
	qemu-devel@nongnu.org, armbru@redhat.com,
	Luiz Capitulino <lcapitulino@redhat.com>
Subject: Re: [Qemu-devel] Re: KVM call minutes for June 8
Date: Thu, 10 Jun 2010 09:27:34 -0500	[thread overview]
Message-ID: <4C10F656.20305@codemonkey.ws> (raw)
In-Reply-To: <4C10E3B2.9070905@redhat.com>

On 06/10/2010 08:08 AM, Kevin Wolf wrote:
> Am 10.06.2010 14:53, schrieb Anthony Liguori:
>    
>> On 06/10/2010 04:43 AM, Kevin Wolf wrote:
>>      
>>> Huh, why this? Seems I still haven't understood all of qcow2 then... I
>>> always thought that there's just a specific offset where VM state
>>> starts, but no explicit end.
>>>
>>>        
>> A live snapshot can last for a very long time.  What happens if you need
>> to allocate a new block for disk I/O while saving a snapshot?
>>      
> You allocate it, I guess?
>
> Note that VM state must be virtually contiguous, but not necessarily
> physically (virtually = on the virtual hard disk as seen by the guest;
> physically = in the image file). It's just not seen by the guest because
> it's saved at a high offset that is after the end of the real disk
> content, but otherwise it should behave the same as guest data.
>    

I guess you could just start writing and then once your finished, you 
could update the snapshot information.  So yeah, I think your right that 
it's doable with the current format.

Regards,

Anthony Liguori

> Kevin
>    

  parent reply	other threads:[~2010-06-10 14:27 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-06-08 15:05 KVM call minutes for June 8 Chris Wright
2010-06-08 15:05 ` [Qemu-devel] " Chris Wright
2010-06-08 16:01 ` Anthony Liguori
2010-06-08 16:01   ` [Qemu-devel] " Anthony Liguori
2010-06-08 20:59   ` Luiz Capitulino
2010-06-08 21:13     ` Anthony Liguori
2010-06-09 15:18       ` Luiz Capitulino
2010-06-09 15:31         ` Daniel P. Berrange
2010-06-09 15:31           ` Daniel P. Berrange
2010-06-09 16:22           ` Anthony Liguori
2010-06-09 16:22             ` Anthony Liguori
2010-06-09 16:29             ` Daniel P. Berrange
2010-06-09 16:29               ` Daniel P. Berrange
2010-06-10  9:43             ` Kevin Wolf
2010-06-10  9:43               ` Kevin Wolf
2010-06-10 12:53               ` Anthony Liguori
2010-06-10 12:53                 ` Anthony Liguori
2010-06-10 13:08                 ` Kevin Wolf
2010-06-10 13:08                   ` Kevin Wolf
2010-06-10 14:11                   ` Avi Kivity
2010-06-10 14:11                     ` Avi Kivity
2010-06-10 14:22                     ` Kevin Wolf
2010-06-10 14:22                       ` Kevin Wolf
2010-06-10 14:27                   ` Anthony Liguori [this message]
2010-06-10 14:27                     ` Anthony Liguori
2010-06-11 12:55                     ` Luiz Capitulino
2010-06-11 12:55                       ` Luiz Capitulino
2010-06-11 13:48                       ` Anthony Liguori
2010-06-11 13:48                         ` Anthony Liguori
2010-06-09 16:26         ` Anthony Liguori

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=4C10F656.20305@codemonkey.ws \
    --to=anthony@codemonkey.ws \
    --cc=armbru@redhat.com \
    --cc=berrange@redhat.com \
    --cc=chrisw@redhat.com \
    --cc=kvm@vger.kernel.org \
    --cc=kwolf@redhat.com \
    --cc=lcapitulino@redhat.com \
    --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.