Linux Rescue over PXE
Brett Lee
=============================


References:
=======================
http://wiki.centos.org/HowTos/PXE/Rescue_PXE
http://www.hps.com/~tpg/notebook/pxe.php
http://www.linuxjournal.com/article/9963
http://www.linuxquestions.org/questions/red-hat-31/rhel4-ident-info-from-nfs-ks.cfg-at-boot-prompt-480531/




=======================
Here goes:
=======================


1.  You've got your TFTP server setup in /tftpboot (or /var/lib/tftpboot or ...)
----------------------------------------------------------------------------------


2.  You've got PXE boot up and working
------------------------------------------

[root@linux tftpboot]# ll pxelinux.0 pxelinux.cfg/default
-rw-r--r--    1 root     root        13148 Nov 14  2008 pxelinux.0
-rw-r--r--    1 root     root          244 Sep 20 13:06 pxelinux.cfg/default
[root@linux tftpboot]#

[root@linux tftpboot]# cat pxelinux.cfg/default
DEFAULT 1
PROMPT 1
TIMEOUT 300
DISPLAY boot/centos5.3.msg

# Memtest
LABEL 1
  KERNEL boot/memtest

# Rescue Disk
LABEL 2
  KERNEL boot/vmlinuz-centos5.3
  APPEND initrd=boot/initrd-centos5.3.img ramdisk_size=100000 text rescue ks=http://install.home.local/centos/5.3/rescue.cfg

# Kickstart
LABEL 3
  KERNEL boot/vmlinuz-centos5.3
  APPEND text ks=http://install.home.local/centos/5.3/centos5.3-ks.cfg ro root=/dev/sda1 initrd=boot/initrd-centos5.3.img
[root@linux tftpboot]#

[root@linux tftpboot]# ll boot/centos5.3.msg boot/memtest boot/vmlinuz-centos5.3 boot/initrd-centos5.3.img
-rw-r--r--    1 root     root          279 Sep 20 16:21 boot/centos5.3.msg
-rw-r--r--    1 root     root      6302756 Sep 20 15:08 boot/initrd-centos5.3.img
-r--r--r--    1 root     root        94600 Sep 20 16:24 boot/memtest
-rw-r--r--    1 root     root      1826484 Sep 20 15:09 boot/vmlinuz-centos5.3
[root@linux tftpboot]# cat boot/centos5.3.msg

================= Boot Options ===================

1. Memtest x86+
2. CentOS 5.3 Rescue
3. CentOS 5.3 Kickstart

==================================================


Select 1, 2 or 3.
Default image will boot in 30 seconds...
==================================================
[root@linux tftpboot]#



3.  You've got Apache serving up files:
-----------------------------------------

<VirtualHost *:80>
ServerName install.home.local
DocumentRoot              /var/www/html/install
CustomLog                 logs/install.log combined
ErrorLog                  logs/install.log
ErrorDocument 401         /missing.html
</VirtualHost>

<VirtualHost *:80>
ServerName 192.168.0.254
DocumentRoot              /var/www/html/install
CustomLog                 logs/install.log combined
ErrorLog                  logs/install.log
ErrorDocument 401         /missing.html
</VirtualHost>



4.  You've got /var/www/html/install as a SYMLINK to your install files
-------------------------------------------------------------------------

[root@linux tftpboot]# ll /var/www/html/install
lrwxrwxrwx    1 root     root            9 Sep 20 12:30 /var/www/html/install -> /data/pxe
[root@linux tftpboot]#


[root@linux tftpboot]# ll /data/pxe/centos/
total 12
drwxr-xr-x    3 root     root        4096 Sep 20 15:12 5.1
drwxr-xr-x    3 root     root        4096 Sep 20 15:12 5.2
drwxr-xr-x    3 root     root        4096 Sep 20 16:45 5.3
[root@linux tftpboot]#


[root@linux tftpboot]# ll /data/pxe/centos/5.3
total 3889706
-rw-rw-r--    1 root     root    3971014656 Sep 20 13:47 CentOS-5.3-i386-bin-DVD.iso
-rw-r--r--    1 root     root      6302756 Mar 20  2009 initrd.img
-rw-r--r--    1 root     root         1770 Sep 20 15:50 ks.cfg
drwxr-xr-x    7 root     root         6144 Mar 20  2009 mnt
-rw-r--r--    1 root     root          508 Sep 20 16:45 rescue.cfg
-rw-r--r--    1 root     root      1826484 Mar 20  2009 vmlinuz
[root@linux tftpboot]#


[root@linux tftpboot]# tail -3 /etc/rc.d/rc.local
if [ -r /data/pxe/centos/5.3/CentOS-5.3-i386-bin-DVD.iso ]; then
  mount -t iso9660 -o loop /data/pxe/centos/5.3/CentOS-5.3-i386-bin-DVD.iso /data/pxe/centos/5.3/mnt
fi
[root@linux tftpboot]#



5.  You've got your rescue.cfg file ready to go
--------------------------------------------------

[root@linux tftpboot]# cat /data/pxe/centos/5.3/rescue.cfg
# Kickstart configuration file CentOS 5.3 Rescue Mode
#
#System  language
#
lang en_US.UTF-8
#
#Language modules to install
#
langsupport --default=en_US.UTF-8 en_US.UTF-8
#
#System keyboard
#
keyboard us
#
#System mouse
#
mouse none
#
#Retrieve rescue system from NFS
#
# nfs --server=$yournfsserverip
# --dir=/directory/that/contains/disc1/CentOS/RPMS
#
#Retrieve rescue system from http
#
url --url http://install.home.local/centos/5.3/mnt
#
#Network information
#
network --device eth0 --bootproto=dhcp

[root@linux tftpboot]#



6.  You've got your ks.cfg file ready to go
--------------------------------------------------

[root@linux tftpboot]# cat /data/pxe/centos/5.3/ks.cfg  | more
# Kickstart file automatically generated by anaconda.

install
#url --url http://mirror.centos.org/centos/5.3/os/i386
url --url http://install.home.local/centos/5.3/mnt
lang en_US.UTF-8
keyboard us
network --device eth0 --bootproto dhcp
rootpw --iscrypted $1$tCFOQlPz$D97gDNp0/mfv2bCGDfPnx0
firewall --enabled --port=22:tcp
authconfig --enableshadow --enablemd5
selinux --enforcing
timezone --utc America/Denver
bootloader --location=mbr --driveorder=hda --append="rhgb quiet"
# The following is the partition information you requested
# Note that any partitions you deleted are not expressed
# here so unless you clear all partitions first, this is
# not guaranteed to work
clearpart --all --drives=hda
part /boot --fstype ext3 --size=100 --ondisk=hda
part / --fstype ext3 --size=25000 --asprimary
part swap --size=2048 --asprimary

%packages
@cluster-storage
@office
@engineering-and-scientific
@mysql
@development-libs
@editors
@system-tools
@gnome-software-development
@text-internet
@x-software-development
@virtualization
@legacy-network-server
@dns-server
@gnome-desktop
@dialup
@core
@authoring-and-publishing
@base
@ftp-server
@network-server
@games
@legacy-software-development
@clustering
@java
@java-development
@openfabrics-enterprise-distribution
@emacs
@legacy-software-support
@base-x
@graphics
@web-server
@ruby
@smb-server
@printing
@kde-software-development
@kde-desktop
@mail-server
@server-cfg
@sound-and-video
@admin-tools
@news-server
@development-tools
@graphical-internet
kmod-gnbd-xen
kmod-gfs-xen
kdepim
perl-XML-SAX
perl-XML-NamespaceSupport
emacs
festival
audit
mesa-libGLU-devel
kexec-tools
bridge-utils
device-mapper-multipath
vnc-server
xorg-x11-server-Xnest
xorg-x11-server-Xvfb
kdegraphics
libsane-hpaio
kdemultimedia
imake
-sysreport
[root@linux tftpboot]#



6.  Finally, you might want to backup/restore a partition
-----------------------------------------------------------

# GET THE IMAGE
1.  PXE boot your Linux and get a Rescue Shell
2.  copy off a filesystem to image using:
    # dd if=/dev/sda1 | ssh nfs.home.local 'dd of=/data/Linux-sda1.img' bs=2048

# RESTORE THE IMAGE
1.  Install new disk and repeat step 1 (above)
2.  Reverse step 2 (above) using:
    # ssh nfs.home.local 'dd if=/data/Linux-sda1.img' | dd of=/dev/sda1 bs=2048



Happy Rescuing !