Booting from USB drives

Rich Ernst rernst at
Wed May 15 07:26:56 PDT 2013

On Wed, May 15, 2013 at 6:09 AM, David Brown <davidb at> wrote:
> On Wed, May 15, 2013 at 05:29:13AM -0700, Franklin Johnston wrote:
>> Regardless, this is a digression from the real question, which is, why
>> would a given USB drive not be bootable? Regardless what Windows is or is
>> not capable of, I am able to demonstrate with Linux that I can install and
>> make bootable at least some drives.
> One possibly test might be to download one of the Linux rescue images
> that have already been setup to boot from USB.  Most of these now can
> just be dd'd directly to the drive and will be bootable (there are
> more complex instructions to allow the drive to be writable, and such,
> but the simple dd is a good test).
> is one of these (you can just dd the iso to the USB
> stick).  You can also boot the Ubuntu livecd this way.  It also has
> pretty detailed instructions on making a custom bootable image.

I didn't see any way to use dd to just write the iso to the usb for

But for Franklin's nonbootable usb stick, here's some info that might
help (and similar to what I wrote a moment ago).


Step 2: Reinitialization of the stick

The following instructions may not be required, it depends on how your
USB stick is configured. So you can try to skip this the first time.
In case of problems getting the USB stick to boot, you should really
try this. Confirm that you have a backup of the data that are on your
stick before you do this. Thanks to jadjay in the forums for this
addition to the instructions. We assume your device is /dev/sdf but
you must replace it with the device name of your own USB stick. Be
very sure that this is the correct device !

First, run cfdisk to check that the partition has the correct ID in
the partition table of your USB stick. Select type LBA FAT32 may be 0B
or 0C, to make it bootable.

cfdisk /dev/sdf

Use mkfs.vfat to format the partition. All data will be erased, so
make sure you don't need the data which it contains.

mkfs.vfat -F 32 -n SYSRESC /dev/sdf1

The following dd command will overwrite the first 404 bytes of the MBR
of your stick. It will erase the previous boot instructions with the
default ones to make sure that it will work. It does not change
anything in the partition table since the partition table starts at
offset 446 in the MBR.

 dd if=/usr/share/syslinux/mbr.bin of=/dev/sdf

Synchronize to make sure that all the changes have been flushed to the disk.


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