[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Qemu-devel] [Qemu-block] Can I only commit from active image to cor

From: Alberto Garcia
Subject: Re: [Qemu-devel] [Qemu-block] Can I only commit from active image to corresponding range of its backing file by qemu cmd?
Date: Thu, 27 Sep 2018 16:23:49 +0200
User-agent: Notmuch/0.18.2 (http://notmuchmail.org) Emacs/24.4.1 (i586-pc-linux-gnu)

On Thu 27 Sep 2018 04:14:15 PM CEST, Max Reitz wrote:
> On 25.09.18 16:13, Alberto Garcia wrote:
>> On Thu 13 Sep 2018 08:37:05 PM CEST, Max Reitz wrote:
>>> First, split .003 into the part we want to commit and the part we
>>> don't want to commit.  This is a bit tricky without qemu-img dd @seek
>>> (or a corresponding convert parameter), so we'll have to make do with
>>> backing=null so we don't copy anything into the output from img.003's
>>> backing chain.
>>> Or, we would have to use backing=null, but for some reason that
>>> doesn't work.  I'll have to investigate.
>>> So rebase will need to do:
>>> $ qemu-img rebase -u -b '' img.003
>>> $ qemu-img convert -O qcow2 \
>>>     "json:{'driver':'raw','offset':0,'size':1048576,\
>>>            'file':{'driver':'qcow2',\
>>>                    'file':{'driver':'file','filename':'img.003'}}}" \
>>>     "json:{'driver':'null-co','size':2097152}" \
>>>     img.003.commit.000
>> If you only want to copy parts of a backing file I think it's much
>> simpler if you use copy-on-read:
> And you can do it at runtime!

How would you do that? As far as I'm aware HMP's qemu-io doesn't allow
you to enable copy-on-read, and block-stream (which uses copy-on-read)
doesn't allow you to specify a range.


reply via email to

[Prev in Thread] Current Thread [Next in Thread]