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Re: [Xen-devel] [PATCH] vhd-util create: add -C|nocow option

Ian Jackson wrote:
> Ian Campbell writes ("Re: [Xen-devel] [PATCH] vhd-util create: add -C|nocow 
> option"):
>> On Thu, 2013-11-21 at 15:46 +0800, Chunyan Liu wrote:
>>> Add '-C' (nocow) option to vhd-util create.
>>> Btrfs has terrible performance when hosting VM images, even more when the 
>>> guest
>>> in those VM are also using btrfs as file system. One way to mitigate this 
>>> bad
>>> performance is to turn off COW attributes on VM files (since having copy on
>>> write for this kind of data is not useful). According to 'chattr' manpage, 
>>> could be set to new or empty file only on btrfs, so add a option here so 
>>> that
>>> users could have a chance to set NOCOW to a vhd image.
>> Is there not some btrfs (or generic) utility which could be used to do
>> this after image creation rather than trying to build it in to every
>> utility which creates an image file?
> This may seem like a daft question, but why do we even have a vhd
> utility in our tree ?  Is there not some vhd tools package that this
> should be in ?

Newer qemu-img supports vhd and vhdx right?  Is there even a need for
this tool at all anymore?


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