Figuring stuff out

Overview

This process depends on the Xen host being CentOS. It could be made to work somewhere else but this is easy and happens to be where I do installs often.

Volumes are created in LVM not image files. Config file will need to be updated to point to the correct VG.

The domu created is a very minimal CentOS 5.4 install.

The create script

#!/bin/bash

if [ "$1" = "" ] ; then
        echo "usage: $0 "
        exit
elif [ ! -f "$1"  ] ; then
        echo "Could not open $1"
        exit
fi

config="$1"
. $config

echo "This script only works when ran on a CentOS system for the moment"
echo -n "Type YES if you want to create $SYSVOL and $SWAPVOL: "
read resp
if [ ! "$resp" = "YES" ] ; then
        exit
fi

set -x

lvcreate --size $SYSVOLSIZE --name $SYSVOL ${VG}
lvcreate --size $SWAPVOLSIZE --name $SWAPVOL ${VG}
mkfs.ext3 /dev/${VG}/$SYSVOL
mkswap /dev/${VG}/$SWAPVOL

mkdir /mnt/server
mount /dev/${VG}/$SYSVOL /mnt/server
mkdir -p /mnt/server/dev /mnt/server/etc /mnt/server/proc /mnt/server/var/lock/rpm /mnt/server/var/lib/rpm /mnt/server/var/log
MAKEDEV -d /mnt/server/dev -x random
MAKEDEV -d /mnt/server/dev -x console
MAKEDEV -d /mnt/server/dev -x zero
MAKEDEV -d /mnt/server/dev -x null
mount -t proc none /mnt/server/proc
wget $CENTOSRPM
rpm --initdb --root=/mnt/server
rpm -ivh --root=/mnt/server --nodeps centos-release*.rpm
#yum groupinstall Core --installroot=/mnt/server
#yum groupinstall Core --installroot=/mnt/server
yum groupinstall $CENTOSGROUPS --installroot=/mnt/server --disableplugin=protectbase --disableplugin=fastestmirror
cp -a base/* /mnt/server
cd /mnt/server
vi etc/fstab etc/resolv.conf etc/sysconfig/network etc/sysconfig/network-scripts/ifcfg-eth0 etc/hosts

Config file

• By default the install is minimal.


• mirror can be set to something local


• volume group can be set per dom0 as needed


• choose memory size etc...

Currently some config options are not being used as I have not ported an old script to create the xen config

Config example:

VG=vg0
SYSVOL=www1-root
SWAPVOL=www1-swap
SYSVOLSIZE=3G
SWAPVOLSIZE=1G
MEMORY=512
VCPUS=1
CENTOSRPM="http://mirror.centos.org/centos/5.4/os/x86_64/CentOS/centos-release-5-4.el5.centos.1.x86_64.rpm"
CENTOSGROUPS="Core"
KERNEL="/var/lib/xen/boot/vmlinuz-2.6.18-164.el5xen.img"

Sample xen config

kernel = "/var/lib/xen/boot/vmlinuz-2.6.18-164.el5xen"
ramdisk = "/var/lib/xen/boot/initrd-2.6.18-164.el5xen.img"
memory = 512
vcpus = 1
name = "www1"
vif = [ '' ]
disk = ['phy:vg0/www1-root,sda1,w', 'phy:vg0/www1-swap,sda2,w']

root = "/dev/sda1"
extra = "fastboot"

on_poweroff = 'destroy'
on_reboot = 'restart'
on_crash = 'restart'

Using Kickstart is nice too as well as using some of the built in install stuff for Xen. CentOS has a nice wiki page - Installing CentOS DomU