Due to budget constraint, my new device doesn’t come with any CD/DVD ROM and PXE compliant NIC. Therefore, I need to rely on the USB hard disk to make it as a boot media to start the OS installation process.

Prerequisite:

1. You must have a USB storage device like flash/pen drive or hard disk. In my scenario, I only have a USB hard disk and I’m gonna make it as a boot disk to kick start the network installation.
2. You should have the Centos installation CD/image.
3. Running Webserver for Kick Start (unattended) OS installation.
4. Running Linux/Unix OS to create the USB boot disk.

Create USB boot disk:

1. Connect you USB device to a running Linux machine and run “dmesg” to identify the device name.
   

   My USB hard disk being recognized as /dev/sdb

   

2. Use “fdisk” to partition /dev/sdb

   

   1. Create 2 partitions
      1. 100 MB for boot image, boot image partition is Primary 1
      2. Remaining for storage, storage image partition is Primary 2
      3. Tag boot image partition as bootable
      4. Set boot image partition type to FAT32 (type number 1)
      5. Save & Exit

      
      
      
      

   2. Format the partition
      1. Format boot image partition as FAT32

      

      2. Format storage partition as EXT3

      

3. Copy required files from Centos CD to /dev/sdb1
   1. Mount /dev/sdb1 to /mnt
      

      [root@localhost ~]# mount /dev/sdb1 /mnt

   2. Copy the contents of /Centos/isolinux to /mnt from the 1^st CD
      (p/s: isolinux.bin, boot.cat and TRANS.TBL are note needed)

      [root@localhost ~]# cp -R /root/Desktop/isolinux/* /mnt/ [root@localhost ~]# cd /mnt [root@localhost mnt]# rm -rf isolinux.bin boot.cat TRANS.TBL

   3. Rename isolinux configuration file to syslinux.cfg
      

      [root@localhost mnt]# mv isolinux.cfg syslinux.cfg

   4. Copy the installer’s initial RAM disk /Centos/images/pxeboot/initrd.img from the 1^st CD to /mnt
      

      [root@localhost mnt]# cp -R /root/Desktop/initrd.img /mnt/

4. Make the USB hard disk bootable. The flash drive must be unmounted in order to work properly.
   1. Umount /dev/sdb1
      

      [root@localhost isolinux]# cd [root@localhost ~]# umount /dev/sdb1

   2. Install the SYSLINUX bootloader on a FAT filesystem
      

      [root@localhost ~]# syslinux /dev/sdb1

   3. Mount /dev/sdb1 & install Grub
      

      [root@localhost ~]# mount /dev/sdb1 /mnt [root@localhost ~]# grub-install –root-directory=/mnt /dev/sdb Probing devices to guess BIOS drives. This may take a long time. Installation finished. No error reported. This is the contents of the device map /mnt/boot/grub/device.map. Check if this is correct or not. If any of the lines is incorrect, fix it and re-run the script `grub-install’. (fd0) /dev/fd0 (hd0) /dev/sda (hd1) /dev/sdb

   4. Verify that the USB hard disk has a /boot/grub directory, if no, create it manually.
      

      [root@localhost ~]# cd /mnt/boot/grub/

   5. Create grub.conf in /boot/grub. Below is a sample config for ‘grub.conf’
      

      default=0 timeout=5 root (hd1,0) title Centos 5.5 Linux Installer kernel /vmlinuz initrd /initrd.img

   6. Umount /dev/sdb1
      

      [root@localhost boot]# cd [root@localhost ~]# umount /dev/sdb1

5. USB hard disk should be bootable by now.
6. Remember to change the BIOS setting to give priority to boot removable device 1^st

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