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Re: [Qemu-devel] using "qemu-img convert -O qcow2" to convert qcow v1 to
From: |
Max Reitz |
Subject: |
Re: [Qemu-devel] using "qemu-img convert -O qcow2" to convert qcow v1 to v2 creates a qcow v3 file? |
Date: |
Tue, 14 Nov 2017 21:44:39 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.4.0 |
On 2017-11-14 21:38, John Snow wrote:
>
>
> On 11/14/2017 03:35 PM, Max Reitz wrote:
>> On 2017-11-14 21:30, John Snow wrote:
>>>
>>>
>>> On 11/14/2017 01:46 PM, Max Reitz wrote:
>>>> On 2017-11-14 19:45, Thomas Huth wrote:
>>>>> On 14.11.2017 14:32, Max Reitz wrote:
>>>>> [...]
>>>>>> Well, do you want to document it? I'd rather deprecate it altogether.
>>>>>
>>>>> Maybe a first step could be to change qemu-img so that it refuses to
>>>>> create new qcow1 images (but still can convert them into other formats).
>>>>> So basically make qcow1 read-only?
>>>>
>>>> Yep, and the actual first step to that is to make it issue a deprecation
>>>> warning when creating qcow v1 images (which is what I proposed). :-)
>>>>
>>>> Max
>>>>
>>>
>>> Deprecation warning is good.
>>>
>>> In future versions you can shimmy it behind a
>>> --no-really-I-want-this-old-format option, I think we ought to support
>>> creating the images for as long as is technologically convenient.
>>
>> Well, at some point you can also demand from users to just dig out some
>> old version of qemu-img to convert their qcow v1 images to qcow2. It's
>> not like they are going to miss out on anything.
>>
>
> As long is convenient. I won't throw a fit that it needs to be around
> forever, but as long as it's sufficiently guarded from use and isn't
> hard to keep around I'd prefer to do that.
>
> I suppose it's just a weak preference.
I agree that sufficiently guarding it (albeit our definitions on what is
sufficient may differ) serves all the purpose I need, that is, make
users aware of the fact that they are doing something for which I can
see no reason.
But on the other hand, I want those guards to make it dead code,
effectively. And if something is dead code... There is no reason to
keep it around.
>> (If you deprecate emulated hardware, users may complain that they don't
>> get the newest qemu features/bugfixes/... while continuing to use that
>> hardware, so I can see that it's a tough decision whether to deprecate
>> that. But it's not like you are going to lose any features or anything
>> if you convert your dusty images to qcow2. On the contrary, we're
>> helping you to get more performance out of them. Maybe qemu should just
>> silently convert qcow v1 images to qcow2 without asking the user, like
>> Apple did...)
>>
>> Max
>>
>
> "Like Apple did" seems sufficient justification to never do that, but
> maybe that's just my own opinion.
Sorry, forgot the emoticon. :-)
Yes, that was meant to be a joke. Although adding a qemu-img amend for
amending qcow v1 to v2/v3 images is probably mostly an issue of creating
the right internal interface for cross-format amendments.
(Silently storing qcow v1 as v2/v3 images is actually something where
users could have a problem because maybe they have some tool that only
works on qcow v1 images; and then they can't use that together with an
auto-amending qemu...)
Max
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- [Qemu-devel] using "qemu-img convert -O qcow2" to convert qcow v1 to v2 creates a qcow v3 file?, Peter Maydell, 2017/11/13
- Re: [Qemu-devel] using "qemu-img convert -O qcow2" to convert qcow v1 to v2 creates a qcow v3 file?, Peter Maydell, 2017/11/13
- Re: [Qemu-devel] using "qemu-img convert -O qcow2" to convert qcow v1 to v2 creates a qcow v3 file?, Eric Blake, 2017/11/13
- Re: [Qemu-devel] using "qemu-img convert -O qcow2" to convert qcow v1 to v2 creates a qcow v3 file?, Eric Blake, 2017/11/13
- Re: [Qemu-devel] using "qemu-img convert -O qcow2" to convert qcow v1 to v2 creates a qcow v3 file?, Max Reitz, 2017/11/14
- Re: [Qemu-devel] using "qemu-img convert -O qcow2" to convert qcow v1 to v2 creates a qcow v3 file?, Thomas Huth, 2017/11/14
- Re: [Qemu-devel] using "qemu-img convert -O qcow2" to convert qcow v1 to v2 creates a qcow v3 file?, Max Reitz, 2017/11/14
- Re: [Qemu-devel] using "qemu-img convert -O qcow2" to convert qcow v1 to v2 creates a qcow v3 file?, John Snow, 2017/11/14
- Re: [Qemu-devel] using "qemu-img convert -O qcow2" to convert qcow v1 to v2 creates a qcow v3 file?, Max Reitz, 2017/11/14
- Re: [Qemu-devel] using "qemu-img convert -O qcow2" to convert qcow v1 to v2 creates a qcow v3 file?, John Snow, 2017/11/14
- Re: [Qemu-devel] using "qemu-img convert -O qcow2" to convert qcow v1 to v2 creates a qcow v3 file?,
Max Reitz <=
Re: [Qemu-devel] using "qemu-img convert -O qcow2" to convert qcow v1 to v2 creates a qcow v3 file?, Eric Blake, 2017/11/13