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

Ian Campbell writes ("Re: [Xen-devel] [PATCH] vhd-util create: add -C|nocow 
> 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 ?


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