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== Preparing the reference computer before making the images ==

=== Choosing a reference computer based on your hardware ===

The reference computer to use for creating the images should have a similar hardware: 
 * It's important the computer has the same architecture, 
 * And the same HDD controller (Windows systems)

=== Partitioning the reference computer ===
* Size:
 * Each operating system partition should have a size smaller than the target size - at least 1 GB. 
 * If you follow this recomendation it won't be necessary to resize the file system (Windows systems). In other case you'll have to do an extra reboot of the system (chkdisk) after finishing the deployment.
 
* Do it with OpenGnSys and don't use the operating system installer program.
 * It's important to partition the reference computer with OpenGnSys instead of the operating system installer program.
 * If you partition the hard disk in the operating system installation process you'll have non-wanted extra partitions (Windows Vista and Windows 7) 
 * With a third party tool you may find incompatibilities and maybe you can't change the size with OpenGnSys.

Each operating system needs some previous steps before generating the image.

== Windows XP-Vista-7 ==

=== Mandatory Steps ===
From the windows terminal (cmd):
  * defrag
  * chkdsk /f

=== Users Privileges  ===
Installation is done with an user of admin group. In our case the users that used the computers will be advanced users group. 

=== Network Configuration ===
We should used a DHCP server to provide the network information to the computers: IP address, network mask, gateway, etc.

In our case, in the server is defined the fixed IP address for every MAC. This allow to indentify exactly the phisic computer from its IP. 

=== XP compatible with different hardware ===
If operating system have installed the drivers for the devices of ours computers, it will be used in all of them, no need to have different images based on hardware.

=== Minimize the size of the image ===
We should clean all that not needed.

'''Delete files used for installations.'''

'''Delete temporary files''':

 * Delete history, cookies, cache, etc from browsers. 
 * Delete in "Documents and Settings" the files created as recently documents, temp, ...

=== Hard Disk Defrag  ===
This will be the last step, the files fragmented in the hard disk, we can group the contiguous disk sectors with the XP utility: "Disk Defrag".

== Linux ==

=== Mandatory Process ===
 * Install in simple partitions. Don't use LVM or RAID.
 * Grub should be installed in the partition boot-sector. Normally, always in the process of Linux installation there is an option to indicate what do you wish to install in the partition boot-sector.

The documentation is done by reference to an Ubuntu 10.04, for others distributions, the location of the files may vary slightly. 

=== Replace uuid by device name ===
Each computer hard disk and partition have an unique identifier. To used the operating system in other computer, this information should be replaced with the device name. 

'''Information of the system partitions: /etc/fstab'''

In general, Ubuntu is able to initiate a system root partition, but can not mount the swap or other partition.

When OpenGnSys start the operating system, changed in the fstab the value of the root partition, but if we started with the grub we should make this change.
{{{
# / was on /dev/sda1 during installation
#UUID=148eba5f-1051-4a3b-acd1-f63750c071cd /               ext3    errors=remount-ro 0       1
/dev/sda2        /               ext3    errors=remount-ro 0       1
}}}


'''Information of boot device: /boot/grub/grub.cfg o /boot/grub/menu.lst'''

If we do not change the boot device information, OpenGnSys may initiate the partition without problems, but if we need start with grub not find it. 

This is an example for grub.cfg: 

{{{
menuentry 'Ubuntu, con Linux 2.6.32-30-generic' --class ubuntu --class gnu-linux --class gnu --class os {
        recordfail
        insmod ext2
        set root='(hd0,2)'
        search --no-floppy --fs-uuid --set 148eba5f-1051-4a3b-acd1-f63750c071cd
        #linux   /boot/vmlinuz-2.6.32-30-generic root=UUID=148eba5f-1051-4a3b-acd1-f63750c071cd ro   quiet splash
        linux   /boot/vmlinuz-2.6.32-30-generic root=/dev/sda2   quiet splash
        initrd  /boot/initrd.img-2.6.32-30-generic
}
}}}

The same change is for menu.lst.

=== Name Computer Info /etc/hostname ===
Contains the name computer. Delete this file because the name computer should be assign by DHCP. 

=== Network Card Info /etc/udev/rules.d/70-persistent-net.rules ===
In this file, we can stored the NIC ethernet address. If the system find another ethernet, it will be renamed. 

The solution is delete this file.  Como se crea automáticamente al entrar en el sistema operativo tenemos que eliminarlo desde el cliente opengnsys justo antes de crear la imagen.

=== Minimize the Image Size ===

We should clean all that do not needed.

'''Delete file from install applications'''
The system saved in /var/cache/apt/archives/, we can delete with:
{{{
sudo apt-get clean
}}}

'''Delete the temporary files'''

Normally, the system does when exit, but not sometimes.
From the OpenGnSys client, delete the content of the directories /tmp and /var/tmp

'''Delete other files'''

We can deleted all used for the installation and all that not needed: trash, cache browser, etc. of all defined users.