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Date: Tue, 28 Jul 2009 10:03:00 +0100
From: Jamie Lokier <jamie@shareable.org>
Subject: Re: [Qemu-devel] [PATCH] Add new block driver for the VDI format (use
	aio)
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To: "Daniel P. Berrange" <berrange@redhat.com>
Cc: Amit Shah <amit.shah@redhat.com>, Kevin Wolf <kwolf@redhat.com>, QEMU Developers <qemu-devel@nongnu.org>, Christoph Hellwig <hch@lst.de>

Daniel P. Berrange wrote:
> > By the way, why is fallocate() support being added to libvirt to
> > improve disk image creation, instead of to qemu-img?
> 
> libvirt has to work with more than just QEMU.  Thus it has a built in
> support for creating raw files, and this is where we added fallocate
> support. It also has ability to call out to hypervisor specific tools
> for creating non-raw formats. We support qemu-img, and qcow-create (the
> latter from Xen)

Ok.  It sounds like fallocate() support would be useful for qemu-img
too (even if libvirt is used to manage it, if it didn't produce it).

-- Jamie