13
5
I am using a windows "standard" ISO file: Win10_1511_1_English_x64.iso and I have verified its md5 matches the expected. The iso is mountable in OS X as a "UDF" format.
I then copy it "straight" to my USB drive, like:
sudo dd if=Win10_1511_1_English_x64.iso of=/dev/rdisk1 bs=1m
then plug it into my dell optiplex 780 (a little old, I know), enable booting from USB device in the BIOS, and choose it, and all I get is:
No boot device available - strike F1 to retry boot ...
What am I doing wrong?
The created USB is readable in OS X, but in other windows boxes, it just says "You need to format the disk in Drive E: before you can use it." So it doesn't boot, nor can windows read it...
Update: I ran the OS X "Boot Camp Assistant" (check the box "Create a Windows 7 or later version install disk" and gave it the same ISO file), then it magically boot fine (appears to be formatted FAT32). Maybe it's some special Dell limitation they can only boot on USB if it's FAT32? Why would it not boot from straight UDF?
1Every windows bootable usb installer I have made since Vista has been fat32, not sure it is a Dell issue though. – Moab – 2016-04-08T22:25:32.060
2The answer is quite right except all the bits about
UDF
. The issue doesn't really have anything to do withISO9660
vsUDF
(and neither isISO files are almost all UDF formatted
true). It's about whether the ISO is made purely as perEl Torito
or "hybridly" including an MBR. – Tom Yan – 2016-04-09T09:14:20.680@TomYan ahh that explains it, thanks! I tried to update it. – rogerdpack – 2016-04-10T01:55:07.643