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Date: Wed, 6 Jun 2018 12:42:28 +0100
From: "Richard W.M. Jones" <rjones@redhat.com>
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Subject: Re: [Qemu-devel] storing machine data in qcow images?
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To: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Max Reitz <mreitz@redhat.com>, Kevin Wolf <kwolf@redhat.com>, armbru@redhat.com, qemu-block@nongnu.org, "Michael S. Tsirkin" <mst@redhat.com>, qemu-devel@nongnu.org, stefanha@redhat.com

On Wed, Jun 06, 2018 at 12:14:07PM +0100, Dr. David Alan Gilbert wrote:
> The problem with having a separate file is that you either have to copy
> it around with the image or have an archive.  If you have an archive
> you have to have an unpacking step which then copies, potentially a lot
> of data taking some reasonable amount of time.  Storing a simple bit
> of data with the image avoids that.

This isn't really true.  For OVA (ie. tar) we don't unpack them.
Adding file.offset and file.size in qemu's raw driver was crucial to
that optimization.

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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