I have always been a fan of stripped down "just what you need" OS installations of Windows and Linux. Which is why we use nLite for creating custom XP builds and gentoo for general purpose linux machines. For Oracle applications we use a base installation of Oracle Enterprise Linux.

The advantage of a these minimal builds are: 

• Better Performance
• Smaller Footprint
• More secure (in theory)

This has worked well for us - our hosted instances boot in a minute or less.

I learnt that there is a whole movement around this called JeOS or "Just the OS" builds for various ubuntu builds. Now Oracle has released a JeOS build for Oracle Enterprise Linux. The purpose behind the release is to help folks to package VMs for Oracle's virtualization product. In fact even Microsoft is releasing a JeOS.

Since I was creating a new build for Essbase and EPM 11.1 for our hosted platform, I decided to try using the JeOS for our base build. It worked out quite well. The image boots up in under a minute (compared to 7 or 8 minutes with the stock EC2 image provided by Oracle). The base installation (without the apps) is under 1GB. Here are the steps to create the image:

Start the Oracle Enterprise Linux AMI: ami-cecb2fa7. 

Download the JeOS rpms from Oracle here. Also download the Oracle Enterprise Linux 5 DVD images and copy all the rpms to /mnt/OEL/Server. I suggest using the wget trick mentioned in this post to download the files directly to the EC2 instance. Install the rpms:

rpm -ivh ovm-modify-jeos-1.0.1-10.el5.noarch.rpm 
rpm -ivh ovm-el5u2-xvm-jeos-1.0.1-5.el5.i386.rpm 
rpm -ivh ovm-template-config-1.0.1-5.el5.noarch.rpm 

Create a directory on the ephemeal storage (/mnt)

mkdir /mnt/jeos
mkdir -p /mnt/jeos/image
mkdir -p /mnt/jeos/rpms

Download some packages needed to simplify installing the rest of the packages on the image:

cd /mnt/jeos/rpms
wget http://apt.sw.be/redhat/el5/en/i386/rpmforge/RPMS/smart-0.52-1.el5.rf.i3...
wget http://apt.sw.be/redhat/el5/en/i386/rpmforge/RPMS/rpmforge-release-0.3.6...
wget http://apt.sw.be/redhat/el5/en/i386/rpmforge/RPMS/rpmforge-release-0.3.6-1.el5.rf.i386.rpm  
cd ..
ls rpms/ > addrpm.lst 

Create the JeOS image using the modifyjeos utility that the rpms from oracle supplied:

modifyjeos -i EL52_i386_PVM_jeos \
-n MyOracleDBTemplate \
-p apt.lst \
-a addrpm.lst \
-m /mnt/jeos/rpms \
-mem 4096 -cpu 2 -S 3072 -I 2048 \
-R 9728 -l /mnt/OEL/ -nogpg

This create a System.img file. Lets mount it:

$ mount -o loop -t ext3 System.img /mnt/jeos/image/
mount: wrong fs type, bad option, bad superblock on /dev/loop6,
missing codepage or other error
In some cases useful info is found in syslog - try
dmesg | tail or so

hmm, the file seems to have multiple partitions, lets check:

$ file System.img 
System.img: x86 boot sector; partition 1: ID=0x83, active, starthead 1, startsector 63, 64197 sectors; partition 2: ID=0x83, starthead 0, startsector 64260, 22539195 sectors; partition 3: ID=0x82, starthead 254, startsector 22603455, 6313545 sectors, code offset 0x48 

Yup. We can mount it by using an offset calculated by the block size times starting sectors:

$ fdisk -lu System.img 
last_lba(): I don't know how to handle files with mode 81a4
You must set cylinders.
You can do this from the extra functions menu.
Disk System.img: 0 MB, 0 bytes
255 heads, 63 sectors/track, 0 cylinders, total 0 sectors
Units = sectors of 1 * 512 = 512 bytes
Device Boot Start End Blocks Id System
System.img1 * 63 64259 32098+ 83 Linux
System.img2 64260 22603454 11269597+ 83 Linux
Partition 2 has different physical/logical endings:
phys=(1023, 254, 63) logical=(1406, 254, 63)
System.img3 22603455 28916999 3156772+ 82 Linux swap / Solaris
Partition 3 has different physical/logical beginnings (non-Linux?):
phys=(1023, 254, 63) logical=(1407, 0, 1)
Partition 3 has different physical/logical endings:
phys=(1023, 254, 63) logical=(1799, 254, 63) 

So 512*64260 gives us the offset:

mount -o loop,offset=32901120 System.img image/ 

Now I use the following script to setup the machine. Note that you will need your private key and certificate files for bundling and uploading to AWS, the last part of the script. Thanks to Tim Dysinger's blog for the basis of the script. I have made this image available if you want to use a JeOS version of Oracle Enterprise Linux - search for cubeflex or full360 amis.

 # Start
rm -rf /mnt/jeos/image/lib/modules/*
cp -Rp /boot/* /mnt/jeos/image/boot
cp -Rp /lib/modules/* /mnt/jeos/image/lib/modules/
cp /etc/bashrc /mnt/jeos/image/etc/
cp /etc/fstab /mnt/jeos/image/etc/
cat /proc/mounts >/mnt/jeos/image/etc/mtab
mount -o rbind /proc /mnt/jeos/image/proc
mount -o rbind /dev /mnt/jeos/image/dev
mount -o rbind /sys /mnt/jeos/image/sys
cat /etc/resolv.conf >/mnt/jeos/image/etc/resolv.conf
# Mount the Oracle Enterprise Linux rpms
mkdir -p /mnt/jeos/image/mnt/OEL
mount -o bind,ro /mnt/OEL/ image/mnt/OEL/

#chroot to the image
chroot /mnt/jeos/image /bin/bash

# Hostname
echo '127.0.0.1 localhost' >/etc/hosts

# Tidy
cd /
rm -rf tmp && ln -sf var/tmp tmp
rm -rf opt && ln -sf usr/local opt
chkconfig --del oraclevm-template
chkconfig --level 0123456 lvm2-monitor off

# Locale
localedef -i en_US -c -f UTF-8 en_US.UTF-8
echo 'LANG="en_US.UTF-8"' >/etc/default/locale

# Update
rm -rf /lib/tls
# Network
shadowconfig on
usermod -p \
`dd if=/dev/urandom count=50 2> /dev/null | md5sum | cut -d " " -f1-1` \
root
mkdir /etc/skel/.ssh
chmod 600 /etc/skel/.ssh
cp -r /etc/skel/.ssh /root
cat >/etc/ssh/sshd_config <<\EOF
Protocol 2
StrictModes yes
MaxStartups 10:30:60
Ciphers aes256-cbc,aes256-ctr
PasswordAuthentication no
ChallengeResponseAuthentication no
Subsystem sftp /usr/lib/openssh/sftp-server
UseDNS no
EOF

# Boot
cat >/etc/rc.local <<\EOF
#!/bin/sh -e
# Root SSH Public Key
mkdir -p /root/.ssh >/dev/null 2>&1
wget -q -O - http://169.254.169.254/2008-02-01/meta-data/public-keys/0/openssh-key \
>/root/.ssh/authorized_keys
chmod -R go-rwsx /root

# Userdata Shell Script
wget -q -O - http://169.254.169.254/2008-02-01/user-data | sh
exit 0
EOF

#Installs (stripped down list from oracle-validated.rpm)
cat >mnt/pkg.lst <<\EOF
compat-db
compat-gcc-34
compat-gcc-34-c++
compat-libstdc++-33
libaio
setarch
sysstat
ruby
curl
libidn
libaio
xauth
perl
ntp
symlinks 
unzip
wget
rsync
EOF 

# Setup Smart
smart channel --add local-EL-rpms name="Oracle Enterprise Linux RPMs" manual=true type=rpm-dir path=/mnt/OEL/Server/ -y;
smart channel --add Dag-Wieers type=rpm-md priority=-5 baseurl=http://apt.sw.be/redhat/el5/en/i386/dag/ -y;
smart channel --add VA-Tech-Extras type=rpm-md priority=-5 baseurl=http://mirror.cs.vt.edu/pub/CentOS/5.2/extras/i386/ -y;
smart channel --add VA-Tech-Base type=rpm-md priority=-5 baseurl=http://mirror.cs.vt.edu/pub/CentOS/5.2/os/i386/ -y;
smart channel --add Dries type=rpm-md priority=-5 baseurl=http://ftp.belnet.be/packages/dries.ulyssis.org/redhat/el5/en/i386/dries/RPMS/ -y;
smart channel --add atrpms name="ATrpms Repository" type=rpm-md priority=-5 baseurl=http://dl.atrpms.net/el5-i386/atrpms/stable/ -y; 
smart install $(cat pkg.lst)

# EC2 tools
cd /tmp
wget http://s3.amazonaws.com/ec2-downloads/ec2-ami-tools.zip
cd /usr/local
unzip /tmp/ec2-ami-tools.zip
ln -s `find . -type d -name ec2-ami-tools*` ec2-ami-tools
chmod -R go-rwsx ec2*
rm -rf /tmp/ec2*

# Cleanup Startup
chkconfig --del oraclevm-template
chkconfig --del kudzu
lvm2-monitor

# Bundle
rm -f /bin/sh && ln -s /bin/bash /bin/sh ; # make bash the default for ec2
modprobe loop ; # bundle image needs this
cat >/usr/local/sbin/image <<\EOF
#!/bin/bash
export EC2_PRIVATE_KEY=/mnt/ec2/pk.pem
export EC2_CERT=/mnt/ec2/cert.pem
export EC2_AMITOOL_HOME=/usr/local/ec2-ami-tools
export AMAZON_USER_ID=********
export AWS_ACCESS_KEY_ID=*******
export AWS_SECRET_ACCESS_KEY=***********
PATH=$EC2_AMITOOL_HOME/bin:$PATH
BUNDLE=oracle-epm-9.3.1.v01
#ec2-bundle-vol -r i386 -u $AMAZON_USER_ID --fstab /etc/fstab \
#-k $EC2_PRIVATE_KEY -c $EC2_CERT -d /mnt --kernel aki-c5e703ac --ramdisk ari-c2e703ab -s 10240 -e /root/.ssh -p $BUNDLE
ec2-upload-bundle -b jeos.full360.com -m /mnt/$BUNDLE.manifest.xml \
-a $AWS_ACCESS_KEY_ID -s $AWS_SECRET_ACCESS_KEY
#rm -rf /mnt/$BUNDLE* /mnt/img-mnt
EOF
chmod 700 /usr/local/sbin/image
symlinks -cdrsv /
rm -rf /var/tmp/* ~/.bash_history
image

# Register & make the ami public (on another machine)
ec2-register jeos.full360.com/oracle-epm-9.3.1.v01.manifest.xml
ec2-modify-image-attribute ami-XXXXXXX --launch-permission -a all