How
to Boot and Run Fedora Linux with a USB Disk
Copyright © 2006 Pu JIAN
Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License,
Version 1.2 or any later version published by the Free Software
Foundation.
DISCLAIMER: No liability for the contents of this document can be accepted. Use the concepts, examples and information at your own risk. There may be errors and inaccuracies, that could be damaging to your system. Proceed with caution, and although it is highly unlikely that accidents will happen because of following advice or procedures described in this document, the author do not take any responsibility for any damage claimed to be caused by doing so.
This document records the steps that the author have taken to install
Fedora Core (FC) on a USB external hard disk, then boot and run Fedora Linux with the USB external hard disk.
The steps are taken basing on the following conditions:
(a) the
USB external hard disk is a blank disk;
(b) the
computer has 1 ATA/IDE internal hard disk but without any existing FC installation; and
(c) no other
USB or SCSI devices are installed or connected to the computer.
Step 1: Specify "expert"
installation mode
Plug the
USB external hard disk to a USB port of the computer.
Put the FC first installation
CD into the CD drive and boot the computer. When
the FC installer shows the prompt, enter
linux expert
This calls up the expert installation mode and the FC installer
will show the detected USB external hard disk.
More Information
The expert mode/option is not shown on the FC installer help screen. |
Step 2: Select
the external hard disk
When
the FC
installer shows the hard disks, the USB
external hard disk is shown as "/dev/sda". Select
the USB external hard disk as the
target disk for installing FC! Make sure the selection is correct, otherwise the internal hard disk will get formatted.
More Information
To play save, some people recommend removing all other hard disks from the computer before commencing the FC installation. |
Step 3: Partition the
external hard disk
The
simplest way is to let the FC installer automatically
partition the external
hard disk. In this case, the external hard disk
will have the following partitions:
| Partition |
Device name |
| /boot |
/dev/sda1 |
| / |
/dev/sda2 |
| /home |
/dev/sda3 |
| swap |
/dev/sda4 |
Mark the "/boot" partition as
bootable. After that, follow the instructions on
screen to do the installation.
Step 4: Specify the
location for installing "grub"
When the FC
installer prompts for the location for installing
"grub", instruct it to install "grub" in the "/boot" partition.
After
that, follow the instructions on screen to complete the
installation.
Step 5: Reboot to "rescue" mode
After
completing the
installation, put the first FC installation CD back to the CD
drive and
reboot the computer. When the FC installer shows the prompt,
enter
linux rescue
When the FC installer shows prompt screens, respond as follows:
| FC Prompt |
Selection |
| Choose language |
English |
| Choose keyboard |
US |
| Start network interface |
No |
| Detect existing Linux installation |
Yes |
| Hint for exit |
OK |
Finally, the FC installer shows a text
mode command shell (i.e "sh").
Step 6: Prepare
an "initrd" image for mounting the USB external hard disk
At
the command prompt, enter the following commands to prepare an
"initrd-usb.img" (i.e. initialization RAM disk image for USB), then move it to the "/boot" partition:
mkdir /mnt/sda1
mount
/dev/sda1 /mnt/sda1
mkdir /mnt/sda2
mount /dev/sda2 /mnt/sda2
chroot /mnt/sda2
mkinitrd -v -f --with=uhci-hcd --with=ohci-hcd --with=ehci-hcd
--with=scsi_mod --with=sd_mod --witth=sg --with=sr_mod
--with=usb_storage initrd-usb.img ``uname -r`
exit
mv /mnt/sda2/initrd-usb.img /mnt/sda1
Note
The mkinitrd command is an one-line command although it may appear to be more than one line on screen. |
Step 7: Edit the "grub.conf" file
At the command prompt, enter the following commands to get access to the "grub.conf" file:
cd /mnt/sda1/grub
Use the "vi" editor to open "grub.conf" and find the following line in "grub.conf":
/initrd /initrd-2.6...._FC5.img
Add a "#" sign at the beginning of that line to comment it out. So the line looks like:
# /initrd /initrd-2.6 ... FC5.img
Insert the following line below the commented line:
/initrd /initrd-usb.img
Fedora Linux will load the "initrd-usb.img" file by default in
subsequent booting.
Step 8: Change BIOS settings
Remove the FC
installation CD from CD drive. At the command prompt, enter the
following command to exit and wait for the computer to reboot:
exit
If
necessary, change the relevant BIOS setting(s) to enable the computer
to boot from USB external hard disk. Save the settings and
reboot.
If the computer can boot from USB external hard
disk and successfully load Fedora Linux, that's all (i.e. skip the
following steps). Otherwise, it is necessary to
complete the steps below.
Step
9: Prepare a "grub boot" floppy and a "grub.conf" floppy
Put
the first FC installation CD back to the CD drive and
reboot the computer. When the installation prompt shows up,
enter
linux rescue
Respond appropriately and wait for the FC installer to show the text mode command shell. See also Step 5 above.
Put a blank floppy disk into
the floppy drive of the computer. WARNING: All the information
on the floppy disk will be erased. DO NOT use floppy disk
with stored information.
At the command prompt, enter the following commands to copy the
required "grub" boot files to make a "grub boot" floppy
disk:
mkdir /mnt/sda2
mount /dev/sda2 /mnt/sda2
cd /mnt/sda2/usr/share/grub/i386-redhat
dd if=stage1 of=/dev/fd0 bs=512 count=1
dd if=stage2 of=/dev/fd0 bs=512 seek=1
Remove the "grub boot" floppy disk from the floppy drive.
Put another blank DOS formatted floppy disk into the floppy drive of the
computer, and enter the following commands to make a
"grub.conf" floppy disk:
cd /
mkdir /mnt/sda1
mount /dev/sda1 /mnt/sda1
mcopy /mnt/sda1/grub/grub.conf a:
Remove the "grub.conf" floppy disk from the floppy drive. It is
unfortunate that the "grub.conf" file cannot be store in the "grub
boot" floppy disk because the "grub" boot files occupy the system
area of the floppy disk.
Step
10a: Manually boot from floppy disks
Remove the FC
installation CD from CD drive. Put the "grub boot" floppy disk in
the floppy drive of the computer. At
the command prompt, enter the following command to exit and wait for
the computer to reboot:
exit
When the "grub" command
prompt shows up, replace the "grub boot" floppy disk by the "grub.conf" floppy disk, then enter:
configfile /grub.conf
More Information
If there is problem with the "grub.conf" floppy disk, it is also
possible to enter the following commands manually at the "grub" command
prompt:
root (hd1,0)
kernel /vmlinuz ro root=LABEL=/
initrd /initrd-usb.img
boot
In the kernel command line above, the root=LABEL=/
parameter instructs the kernel to find the root partition by label (i.e
name). If there is no existing FC installation in the
computer when FC was being installed on the USB external hard disk, the
default label of the root partition would be "/".
To find the label of each partition, enter to following commands at the command prompt of the rescue screen:
mkdir /mnt/sda2
mount /dev/sda2 /mnt/sda2
cat /mnt/sda2/etc/fstab
Note: If the "sda2" partition has been mounted as above, the mkdir and mount commands mentioned above are not necessary.
If the root partition label on the USB external hard disk is not "/",
it is necessary to change the parameter accordingly, for example:
kernel /vmlinuz ro root=LABEL=/1
kernel /vmlinuz ro root=LABEL=/12
root (hd1,0)
kernel /vmlinuz ro root=/dev/sda2
initrd /initrd-usb.img
boot
|
More Information
If the USB external hard disk would be used to boot and run Fedora Linux on different computers, replace the kernel command line mentioned above by
kernel /vmlinuz ro root=LABEL=/ 3
The last parameter 3 instructs Fedora Linux to run in
Level 3, which will show a text mode command shell (i.e. bash) with a
login prompt. Login as usual.
Assuming
that appropriate graphical screen configurations have been specified in
the "X86Config" file to suit the graphical hardware of different
computers, enter the following command to start the graphical
desktop with desired screen configuration:
startx -- -Screen screen-name
The screen-name is the pre-set screen name in the "X86Config" file.
|
Step 10b: Manually boot from CD
Using 2 floppy disks is inconvenient. After loading Fedora Linux successfully,
it is possible to make a "grub boot" CD with the "grub.conf" included.
See "grub" documentation on how to make such CD; launch a
console, enter
info grub
One point to note, the "menu.lst" file mentioned in the "grub"
documentation is actually the "grub.conf" file. So just take
"grub.conf" as if it is "menu.lst".
Put the "grub boot" CD in the CD drive of the computer. When "grub" shows the command prompt, enter:
configfile /grub.conf
The above steps are for installing Fedora on and booting Fedora from a USB
external hard disk. For feedbacks, please send e-mail to [email protected] .
Last update: October 2006