On Wed, 06 Mar 2019 07:50:21 +0100, R.Wieser wrote:

> Hello all,
>
> I'm intending to do a raw backup (alike DD do if I'm not mistaken) of
> the SD card on a Windows machine and than zipping it.  For that reason I
> would like to clear all unused sectors before making the copy, as than
> the zipping will result in the smallest possible file.
>
> Q: Does Stretch have a program available which can do that, and if so
> which is it ?
>
> Regards,
> Rudy Wieser

Not what you asked for, but I have used 'partimage' on linux systems for
years. It will back up the used sectors of a partition. It can also
compress the image and/or backup over the network. It is linux only, and
seems not to be in the raspbian repository. You could use a linux live cd
on your win machine to do it - or you could download the source and build
it on your raspbian. I first became aware of partimage several years ago
when I wanted to upgrade the hard drive on a laptop. Copied out the
image, partitioned the new drive and copied back - as I recall it can
restore an image to a larger partition with no hassle.

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