While Paul Thurrott was playing with the official Windows 7 USB/DVD Download Tool, creating a bootable USB stick for his netbook upgrade, he ran into an interesting snag with certain discs. The tool, when directed to use an ISO dumped via ImgBurn, would error out. Everything was to UDF spec, so what was going on here?
I’m not a UDF expert, hell not even a novice, but I skimmed through ECMA-167 and the reflected tool code. It appears there are two (possibly more) “navigation buoys” within UDF-formatted ISOs that point to important chunks of the image called Anchor Volume Descriptor Pointers (AVDPs). The first AVDP is somewhere near the top of the image. The last AVDP is located in what appears to be the last logical block of the image. (My guess is this is to support bi-directional reading.)
So assuming each logical block of the image is 2048 bytes large, one could also assume the last logical block is –2048 from the end of the file, right? Well, that’s what the tool assumes. It checks for the last AVDP at the start of the last logical block, doesn’t find it, and bombs out.
I haven’t read through the entire spec., but I doubt there’s anything in here regarding the container of the UDF formatted data.
While one could argue Microsoft Store-downloaded ISOs are comprised in a compatible manner and therefore this scenario is unsupported it wouldn’t have been hard to add some AVDP seeking code.
As a quick hack to resolve this issue, I wrote a tool that merely finds the AVDP in your ISO file and copies it to offset (EOF-2048). This will allow you to use your own ISOs with the Microsoft tool. Microsoft.NET 2.x or higher required.
hi,
This is what I did…format the USB as NTFS and copy/extract files to USB n change boot sequence to USB and VOILA !!!…You are ready to install via USB
I get the same error as kevin posted “i can’t get the nagendra method to work for the Asus PC boot disk,… the windows 7 tool goes one extra step till it gets to the formatiing USB stage of the process, stays at 0% and then says “unable to copy, check usb and the selected ISO and try again”” i have got 2 sperate versions of the img file neither work and i went out and bought a usb so i dont think its that,anyone have a solution?
In response to my own question and kevins i found a website and i was able to use the windows tool.
“Here is what you have to do. Launch a command prompt with admin rights and run the diskpart tool:
diskpart
list disk
select disk #
clean
create partition primary
select partition 1
active
format quick fs=fat32
assign
exit
The “list disk” command will show you the connected drives and with “select disk”, you can choose your USB stick. Be careful to select the right drive or else your day won’t have a happy end. The crucial step here is the “clean” command. It overwrites the MBR and the partition table (thereby, deleting everything on the stick). My guess is that WUDT misses this step and only formats the flash drive. It appears my memory stick had some odd partitions (which is not uncommon). When I tried WUDT again with this prepared stick, the Open Source tool mastered its task without further murmur.”
Hope that helps
This tool works great! Thanks a lot!
Suppeeer. With PowerIso (UDF) the windows tool works very fine. You can do the same with UltraIso :) !
thx for you comments.
cya
Nagedra RockS! Power ISO worked for me
Stick CORSAIR BOOT WINDOWS 7 ? …NO BOOT : SYSTEM: Motherboard – ASUS P4C800-E Deluxe ………STUPID NOOOO BOOT WINDOWS7 FROM STICK . SORY Gyandarmul@yahoo.com .
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