SWATTEC : Home Page > Tutorials and Help for Others > Linux on Netbooks > 4 - Customization

Please Note: While this content is relevant to the SUSD SWATTEC program, the http://ubermix.org website is the formal location for up-to-date content and information on the ubermix Linux build, downloads, etc. The current customization page is at http://ubermix.org/customization.html

Design Overview

To understand how to customize the default setup, it is important to first understand how the quick recovery process works. This install uses a storage scheme called UnionFS, which looks like this:

Logically, the storage on the system is divided into two slices: the system software and settings on the left, and the user's files on the right (commonly referred to as the user's "home"). Physically, however, the storage is actually divided into three slices. The two that are part of the UnionFS setup are the left, labeled "User Changes" and "Default System". What UnionFS allows us to do is create a single logical storage space by combining two physical partitions, one of which is read only ("Default System" above) and one which is read/write ("User Changes" above). Any time the user makes any changes, they are all written to the "User Changes" space. No changes are ever made to the "Default System" space. So, when we want to restore the system to its default settings, we simply erase the "User Changes" space (using the process described in 3 - Basic Usage), and all is back to normal. The beauty of this is two-fold: the system can be restored to default settings in a matter of seconds, and the action is relatively non-destructive, as none of the user's documents in "User Home" are touched.

It is important to note that there are a number of application specific settings that are stored in the user's home folder. Therefore, if we want our restore to work well we also need to restore these settings when we do a factory restore. To facilitate this, default user settings are stored on the "Default System" space in a directory called "/home", and automatically copied into the user's home folder when a factory restore is performed (regardless of the option selected). This is relatively non-destructive, as any files added by the user will not be lost. Some end user settings may be overwritten, however.

In summary, the restore process performs the following steps:

1. Formats the "User Changes" partition, erasing any OS related changes.
2. Copies all the files from within "Default System"/home to the "User Home" space

There are two ways to customize the installation for your environment. If you plan to simply change some settings and add a few applications, then Simple Updates is the way to go. If you plan to make more drastic changes, such as removing applications, then Rebuilding the Base Image is where you will want to go. 

Simple Updates - Now Uber-Easy!

Please note: These instructions have changed as of version 0.702 of the ubermix-key. If you are using an older version, please click on "History" at the top of this page and select a version of this document older that 5/14/2010. 

The Simple Update method is quick and very easy to implement, as it simply copies all necessary files from the "User Changes" and "User Home" spaces (see image above) into two files on the Ubermix key, called "mods.tar.gz" and "user.tar.gz". It is an ideal solution for handling minor modifications to a default system setup, such as setting up printers, installing a few additional applications, adding some files to the user's home folder, and making modifications to the user interface. The beauty of this approach is that, once created, these files can be copied to other ubermix install keys to create a specialized setup for a small number of machines (like a lab) without modifying the default configuration that is the basis for all of your devices. Since the files are generally small, the whole process can be completed quickly and easily. 

For example, the default key already has modification files for the SUSD SWATTEC program on it, which are an excellent example of the Simple Updates process. These modifications include the following:

• Add iTalc Client software, which enables the teacher to monitor, control, and manage all student laptops in an easy to use console.
• Customizes the categories and icons, removing unnecessary icons from the interface
• Adds an icon to "Show System ID", which displays the netbook's host name, which makes the addition of workstations into the teacher's iTalc console easier.
• Adds a script to /etc/network/ifup.d that executes a script in the user's home folder called .network-autostart (also added), which downloads a script file from a web server and executes it. This script enables mass updates and configuration changes.

Please Note: This process is NOT for making significant changes to the default system, such as adding more than a few small applications, or removing applications. If you plan to delete programs or add significant amounts of data, you should not use this method. Follow the steps under "Rebuilding the Base Image" beneath this section for details on how to make significant modifications to the ubermix install. If you are interested in starting with the SWATTEC updates on your netbooks, see http://community.saugususd.org/swattec/page/About+the+SUSD+Updates for important details.

Step-by-Step

The process for creating simple updates is, well, simple. Follow the steps below to create your own simple update files: 

1. Restore your netbook to factory settings by following the instruction in 3 - Basic Usage. Be sure to choose option 2, "Restore unit completely" - it is important that we start the process with a blank slate.
2. Make all the changes you wish to make. For example, you can use "Main Menu" under "System" (alacarte from the command line) to change the icons and categories that appear in the launcher. Or use "Ubuntu Software Center" or "Synaptic Package Maneger" under "System" ("sudo software-center" or "sudo synaptic" from the command line) to add a few new applications (remember - DO NOT remove any applications when creating simple updates files). Keep in mind that you only have about 300Mb of free space on the Default System space, so don't over do it.
3. Run any new applications to make sure that they work, and make appropriate changes to their preferences as needed.
4. Insert your ubermix-install key and reboot your system, booting from the key in the same fashion as you did when you originally installed the system (see 2 - Download and install for details.)
5. When the menu appears, select option "5. Expert Options"
6. From the next menu, select option "2. Create simple updates files using this machine as a model"

That's it! Reboot your machine normally, and you will find updated "mods.tar.gz" and "user.tar.gz" files on your ubermix key.

Extremely Important: Wait for your machine to reboot completely and eject the ubermix install key properly before removing it, or you will be left with a corrupted install key.

Rebuilding the Base Image - Now Uber-Easy!

Please note: These instructions have changed as of version 0.702 of the ubermix-key. If you are using an older version, please click on "History" at the top of this page and select a version of this document older that 5/14/2010. 

Rebuilding the base image is not difficult, but is a bit more time consuming. Choose this option if you will be deleting applications from the default install, or plan to make significant changes. For best results, you should always perform these steps on your smallest netbook. For example, if you have flash-based EeePC 901s and hard disk based EeePC 1000s, create the image on an EeePC 901 if you want to create one image for use with both machines.

It is important to keep in mind that the "Default System" space (see above) is only about 4Gb in size and typically has only about 300Mb of free space left. If you believe that you will need more than 300Mb of space to install everything you want, you should consider Resizing the Base System Partition first (instructions below). Keep in mind that some netbooks (EeePC 901/1000 series, in particular) have only 4Gb of space for their system drive, in which case resizing the base system partition would not work.

To rebuild the base image, we will boot the system with UnionFS turned off, make our changes, do a little prep work, and overwrite the image file on the key with our new image.

1. Restore your netbook to factory settings by following the instruction in 3 - Basic Usage. Be sure to choose option 2, "Restore unit completely" - it is important that we start the process with a blank slate.
2. Reboot the computer and press ESC immediately after your computer manufacturer's splash screen disappears (you should see a flashing cursor in the top left corner for a few seconds - press the escape key within 3 seconds to view the menu.)
3. Select "Normal Boot" from the menu (but don't press enter) and press the "e" key on your keyboard
4. Select the line in the box that begins with the word "initrd" and move the cursor to the end of the line. Backspace over the four letters "aufs" and replace them with "generic". Do not add any spaces.
5. Then press "ctrl+x" on your keyboard to boot
6. The system will boot with the User Changes space disabled, allowing you to run directly from the (ordinarily locked) "Default System" space (see above). Make all the changes you wish to make. For example, you can use "Main Menu" under "System" (alacarte from the command line) to change the icons and categories that appear in the launcher. Or use "Ubuntu Software Center" or "Synaptic Package Maneger" under "System" ("sudo software-center" or "sudo synaptic" from the command line) to add or remove applications. 

Once this is complete, we will need to do some prep work before creating the image. Do the following:

1. Insert your ubermix-install key and reboot your system, booting from the key in the same fashion as you did when you originally installed the system (see 2 - Download and install for details.)
2. When the menu appears, select option "5. Expert Options"
3. From the next menu, select option "1. Update the image on the key using this machine as a model". Note that this process takes a fair amount of time. Since most systems will turn off their displays after a brief period of inactivity, you may find that your screen goes black unexpectedly. If that happens, simply press a "shift" or "ctrl" key to wake the screen back up.

That's it! The image process will take some time, but once it is complete, the base image on the key will now match your custom settings. 

Extremely Important: Wait for your machine to reboot completely and eject the ubermix install key properly before removing it, or you will be left with a corrupted install key.

Important note: Once you modify the base image, the simple update files on the key will probably be obsolete, so don't do simple updates without first updating those files as per the instructions above. 

Resizing the Base System Partition - New!

If you have a system with a large primary storage disk and require additional space in the "Default System" space (see above), you can now increase the size of that partition (hereafter referred to as the "Base System Partition") using your ubermix install key. Keep in mind that if you plan to Rebuild the Base Image (see above) after resizing, you should try to keep the size of the Base System Partition as small as possible, as a large partition will require more space on your ubermix install key. A good rule of thumb for sizing is to make the Base System Partition no larger than twice the size of the ubermix install key, as it will otherwise not fit on the key. Also, a larger Base System Partition will take longer to create and longer to install, so don't make it unnecessarily large.

Important note: DO NOT attempt to resize the Base System Partition on a computer that does not have a large primary disk. For example, EeePC 901/1000 series netbooks only have 4Gb of total space on their system disk, with another 12Gb on a separate disk. This process will fail on such a system and require you to reinstall the ubermix from scratch.

Warning: The resize process deletes the "User Home" space (see above) as part of the resize process. This means that any user data in that space will be lost. Be sure to back up anything you want to keep from the home folder prior to resizing the Base System Partition.

Resizing the base system partition is quite simple using the resize option on the ubermix install key:

1. Insert your ubermix-install key and reboot your system, booting from the key in the same fashion as you did when you originally installed the system (see 2 - Download and install for details.)
2. When the menu appears, select option "5. Expert Options"
3. From the next menu, select option "3. Resize the base system partition"
4. Answer the prompts accordingly

This process can take a fair amount of time, so be sure to plug a netbook/laptop in to the wall while resizing. Since most systems turn off their displays after a brief period of inactivity, you may find that your screen goes black unexpectedly. If that happens, simply press a "shift" or "ctrl" key to wake the screen back up. On older versions of the Ubermix key (prior to version 0.909), at the end of the resize process you will be prompted with a question asking you if you want to "Alter the key". If you plan to Rebuild the Base Image on this key using this machine as a model (see above), choose "Yes". If, however, you are just resizing for personal use and wish for your ubermix install key to remain intact, choose "No." Newer versions (v0.909 and above) modify the key automagically when you update the key according to the instructions in "Rebuilding the base image" above.

Resizing the Ubermix Key to Accommodate a Larger Base System Partition

Once you have resized your Base System Partition (see above), Updating the Base Image (see above) will naturally become a problem, as the default ubermix key install only uses up 2Gb of a USB key, regardless of the size of the key. To accommodate a larger Base Image, you will first need to increase the available space on your ubermix key. To do so, we will use a tool called "GParted".

1. Working from a computer with the ubermix key already installed, use "Synaptic Package Manager" under "System" to locate and install GPartEd. 
2. Once installed, insert your ubermix key and open "GParted" under "System" on your computer.
3. In the top right corner of the window that appears, select your ubermix key from the pop-up menu. Note that it will not be explicitly identified - look for a disk that is the same size as your ubermix key and select it.
4. In the partition list at the bottom half of the window, locate the partition labeled "UBERMIX" and right-click on it. Select "Unmount" from the menu that appears.
5. Right-click again on the partition labeled "UBERMIX" and select "Resize/Move" from the menu that appears
6. Increase the "New size" until it uses all the free space on the disk and click "Resize/Move"
7. Click on the "check mark" at the top of the window to resize the partition.

Once complete, your ubermix key will be resized and ready to accommodate a larger Base Image.

jklein, 05/16/12 04:41 (GMT)