[Libguestfs] [PATCH] v2v: Add --print-estimate option to print source size estimate.
Richard W.M. Jones
rjones at redhat.com
Wed Aug 15 10:26:18 UTC 2018
On Tue, Aug 14, 2018 at 09:31:06PM +0300, Nir Soffer wrote:
> On Tue, Aug 14, 2018 at 8:29 PM Richard W.M. Jones <rjones at redhat.com>
> wrote:
>
> > This option prints the estimated size of the data that will be copied
> > from the source disk.
> >
> > For interest, the test prints:
> >
> > 3747840 ../test-data/phony-guests/windows.img
> > Estimate: 3710976
> >
>
> Why not use qemu-img measure on the overlay?
Yes this would be better, but oddly it doesn't work properly when
the output format is set to 'raw':
/usr/bin/qemu-img 'measure' '-f' 'qcow2' '-O' 'raw' '--output=human' '/home/rjones/d/libguestfs/tmp/v2vovl62b7c2.qcow2'
required size: 6442450944
fully allocated size: 6442450944
However it's OK if the output format is set to 'qcow2':
/usr/bin/qemu-img 'measure' '-f' 'qcow2' '-O' 'qcow2' '--output=human' '/home/rjones/d/libguestfs/tmp/v2vovla53d7c.qcow2'
required size: 1047986176
fully allocated size: 6443696128
I guess it ignores sparseness of raw images, but I can't see a way to
specify that on the command line.
OTOH the qcow2 figure is probably a good enough guess for our purposes
(ie. estimating how much data will be copied).
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
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