i'm trying to create a (bootable) ISO (which i'll then burn to dvd) from the source being an bootable USB disk (it contains windows 7 and i've installed a number of PC's from it already).

So i'm trying to use dd to make the iso.

So first up I'm trying to find the mount info :-

df -h

Filesystem      Size   Used  Avail Capacity  Mounted on
/dev/disk0s2   120Gi   82Gi   37Gi    69%    /
devfs          191Ki  191Ki    0Bi   100%    /dev
map -hosts       0Bi    0Bi    0Bi   100%    /net
map auto_home    0Bi    0Bi    0Bi   100%    /home
/dev/disk0s4   112Gi  4.0Mi  112Gi     1%    /Volumes/BOOTCAMP
/dev/disk2s1   7.5Gi  3.1Gi  4.4Gi    42%    /Volumes/WINDOWS 7

Next, I try the following (from the Desktop folder...) :-

dd if=/dev/disk2s1 of=win7.iso

and I get the error message

dd: /dev/disk2s1: Resource busy

Can anyone help?

  • Have you tried unmounting it before running dd?
    – rodrigo
    Sep 27, 2011 at 13:42
  • yes - when I eject it, the df command doesn't show the usb any more?
    – Pure.Krome
    Sep 27, 2011 at 22:59
  • but if ejected you will not be able to read it! try umount /dev/disk2s1 instead.
    – rodrigo
    Sep 28, 2011 at 11:12

1 Answer 1


I've found my own answer.

I ended up typing

dd if=/dev/disk2 of=~/win7.iso

Note 1: The usb is disk2, not disk2s1. No idea why? Obviously, I do not understand the output of the df command.

Note 2: I had to make sure I used a correct writable path, for the output file.

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