CentOS Bootable USB

All of the gui driven iso to usb programs were not working correctly for me on CentOS.  This document outlines steps to make a CentOS 6 install usb stick.   

What you need:

An 8GB or higher usb stick ( I like corsair voyagers )
CentOS 6.6 DVD 1, 2 and Net Install isos ( www.centos.org )
root

The USB Stick will have 2 partitions. One partition will be bootable, and be used to load the boot menu. The other partition will hold the isos, some necessary files, and kickstart scripts.

Create the following directories:
/tmp/boot
/tmp/modboot
/tmp/iso
/tmp/usb

Mount the minimal boot iso file to the newly created directory:

# mount -o loop /location/to/minimal-boot.iso /tmp/boot

Copy all files from the iso into the modification directory.

# cp -pr /tmp/boot/* /tmp/modboot/

Unmount the ISO.

# umount /tmp/boot

Add entries to the boot menu. The entries will load the installer and tell it to select the proper iso file as an installation source.
If you want a custom backsplash for the menu create a 640X480 image and put it in the same directory as isolinux.cfg. 
We need to modify the file: /tmp/modboot/isolinux/isolinux.cfg
This file lists all of the boot menu entries that will load the installer.
      
[root@kaneda isolinux]# cat isolinux.cfg
default vesamenu.c32
#prompt 1
timeout 600

display boot.msg

menu background splash.jpg
menu title Welcome to CentOS 6.6!

label local
  menu label Boot from ^Local drive
  menu default
  localboot 0xffff

label usbinstaller
  menu label ^Install CentOS 6.6 from the USB Stick
  kernel vmlinuz
  append initrd=initrd.img repo=hd:sda2:/

label kickstart
  menu label ^Kickstart install CentOS 6.6 from the USB Stick
  kernel vmlinuz
  append initrd=initrd.img ks=hd:sda2:/ks.cfg

label vesa
  menu label Install from USB with ^basic video driver
  kernel vmlinuz
  append initrd==initrd.img repo=hd:sda2:/ xdriver=vesa nomodeset

label rescue
  menu label ^Rescue installed system
  kernel vmlinuz
  append initrd=initrd.img rescue

label memtest86
  menu label ^Memory test
  kernel memtest
  append –

# yum -y install genisoimage syslinux
       
# cd /tmp/modboot

# mkisofs -o /tmp/bootusb.iso -b isolinux/isolinux.bin -c isolinux/boot.cat -no-emul-boot -boot-load-size 4 -boot-info-table -R -J -V “CENTOS-6-USB-INSTALLER” -T .

Make the iso bootable.
  
# isohybrid /tmp/bootusb.iso
  
Getting the iso onto the USB stick will wipe the drive.
 Copy over the iso with the command below.

# dd if=/tmp/bootusb.iso of=/dev/sdb bs=4M; sync

May take a while.

Create a new ext4 partition on the USB stick.
This will be used to store the installation iso’s and all other additional content.
   
# fdisk -cu /dev/sdb
# Press ‘n’
# Press ‘p’
# Press ‘2’
# Press Enter twice.
# Press ‘w’
# mkfs.ext4 /dev/sdb2
   
Mount it:

# mount /dev/sdb2 /tmp/usb

Mount the install DVD iso.

# mount -o loop /location/of/installation/iso /tmp/iso
   
Create a directory on the flash drive called images:
   
# mkdir /tmp/usb/images
   
The purpose of this directory is to contain information about the install media. The file we need is install.img.
       
# cp /tmp/iso/images/install.img /tmp/usb/images/
   
Unmount the install iso.

# umount /tmp/iso
   
Copy over any kickstart files, and isos.  See kickstart example below.
   
# cp /location/of/isos /tmp/usb
   
Change the permissions of files and directories on the flash drive.
   
# cd /tmp/usb
# find ./ -type f -exec chmod 444 {} ;
# find ./ -type d -exec chmod 555 {} ;

Unmount the USB drive, and boot.
# umount /tmp/usb

__________________________________

#ks.cfg file
#platform=x86, AMD64, or Intel EM64T
#version=DEVEL
# Firewall configuration
firewall –disabled
# Install OS instead of upgrade
install
# Use hard drive installation media
harddrive –dir=/ –partition=sda2
# Root password
rootpw –iscrypted #;laksjdf;alskdjf;alskjdf;lkajsdf;lkajsdf
# System authorization information
auth  –useshadow  –passalgo=sha512
# Use text mode install
text
# System keyboard
keyboard us
# System language
lang en_US
# SELinux configuration
selinux –disabled
# Do not configure the X Window System
skipx
# Installation logging level
logging –level=info
# Reboot after installation
reboot
# System timezone
timezone –isUtc Etc/UTC
# Network information
network  –bootproto=dhcp –device=eth0 –onboot=on
# System bootloader configuration
bootloader –location=mbr –driveorder=sda
# Partition clearing information
clearpart –all –drives=sdb –initlabel
zerombr
ignoredisk –only-use=sdb
# Disk partitioning information
# With a single disk, partition it into three sections: /boot, /, and swap
part swap –size=2048 –ondisk=sdb
part /boot –fstype=ext4 –size=256 –ondisk=sdb
part / –fstype=ext4 –ondisk=sdb –asprimary –grow –size=1

%packages
bison
cmake
file-devel
flex
gcc
gcc-c++
libpcap-devel
make
openssl-devel
python-devel
swig
zlib-devel

%end