Preparing a USB key for installation

[Phil Meyer]

Julius Maclean wrote:
> Hi Chaps,
>
> First post. Appologies in advance if this is the wrong list. This concerns installation of Fedora based distros from a USB key. I've read the guides that say one should run;
>  dd if=diskboot.img of=/dev/sda
>
> This works fine and I've been able to install OS using this method. However the partition table that this command creates is rather unusable for any thing other than installations. [output of fdisk -l listed below].
>
> It seems as if the USB key is partitioned in such a way that all of the nth scsi device is used. It would be nice to be able mount the USB key in order to say, out an iso image on it. Bit of a waste of a 1GB USB key in that I do have the sapce for diskboot.img *and* an iso image.
>   

The BIOS can divide USB devices into 4 types:
1. USB Floppy
2. USB ZIP
3. USB CDROM
4. USB DISK

Some BIOS manufacturers glob them all together and test each type in turn.

So, the more of these that a single device can satisfy, the more likely 
that it will be bootable.

When you dd the .img to the entire drive, most BIOSs will see it as a 
super floppy, which is #1 on the compatibility list.

It is necessary to know a bit about ZIP drives.  They boot from 
partition 4, and have specific geometry.  Sometimes the geometry 
matters, sometimes it does not.

We have had reasonable success with creating a 13MB partition 4, and the 
remainder on partition 1.
Make partition 4 bootable with the boot flag.
Then dd the .img file to partition 4.
mkfs -t vfat on partition 1
mount and copy the iso(s) to partition 1

There is a current bug in anaconda that seems to cause grub to be 
installed into the MBR of the USB drive when you install this way, and 
if the USB drive during install is read by the BIOS as a disk drive.  
Quite a nasty problem.

Using the recent (very cool) program pungi, the process of building 
custom iso(s) can be automated.

The program pungi is followed in the buildsys list.