more detailed description of Image file handling and backup

lsa-pucrs · Jan 11, 2018 · 9620847 · 9620847
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diff --git a/docs/source/rpi/index.rst b/docs/source/rpi/index.rst
@@ -12,7 +12,7 @@ Setting Up the Raspberry Pi
 
 .. toctree::
 
-   Installing the OS <os-install>
+   Image Handling <os-install>
    Setting Up the OS <setup-os>
    Installing ROS <ros>
    Installing GAMS/MADARA <gams-madara>

diff --git a/docs/source/rpi/os-install.rst b/docs/source/rpi/os-install.rst
@@ -1,11 +1,219 @@
 
 =============================================
-Installing the OS
+Image Handling
 =============================================
 
 
-- download the OS. write down the reasons to choose this os distribution
-- how to burn the sdcard
-- how to the partitioning
-- how to resize the image
+  This section presents how to burn a Linux image into a SDcard and also to backup the SDCard. 
+  It has foucus on RPi, but it should work for any Linux based embedded computer.
 
+
+Download OS
+------------
+
+Oficial Ubuntu MATE 16.04 for Raspberry Pi 3
+https://ubuntu-mate.org/raspberry-pi/
+
+Ubuntu MATE 16.04 with ROS Kinetic for Raspberry Pi 3
+http://www.german-robot.com/2016/05/26/raspberry-pi-sd-card-image/
+
+Oficial Ubuntu MATE 16.04 for Odroid XU4
+https://wiki.odroid.com/odroid-xu4/os_images/linux/start
+https://odroid.in/ubuntu_16.04lts/
+
+Unzip the Image file and go on to the next part.
+
+Burn the Image using Windows
+------------
+
+ Use Win32DiskImager for writing and reading Image files.
+
+
+Burn the Image using Linux
+------------
+
+Execute `lsblk` or `df -l` to find out the mouting palce for the SDCard. It should be `/dev/sdX`, most probably `/dev/sdb` if your computer has only one disk.
+
+
+There are several programs to burn the SDcard. dd is most well known but there are newer options such as `ddrescue` or `dcfldd`.
+
+``
+	sudo ddrescue -D --force ubuntu-mate-16.04.2-desktop-armhf-raspberry-pi.img /dev/sdx
+``
+
+
+``
+    sudo dcfldd of=/dev/sdb if=~/MyImage.img
+``
+
+Force a synchronise of any outstanding input or output, then the card will be safe to remove. 
+
+``
+    sudo sync
+``
+
+That's it.
+
+
+
+Expand the Image Size to Match the SDCard Size
+------------
+
+For Raspberry Pi, execute 
+
+``
+sudo raspi-config
+``
+
+and select 'Expand Filesystem'. 
+
+or, in the command line
+
+``
+sudo raspi-config --expand-rootfs
+sudo reboot
+``
+
+For other embedded computers (e.g. ODroid), execute: 
+
+
+TO BE DONE
+
+
+Backing Up an Image File
+------------
+
+Once your embedded computer is fully configured, it is a good ideia to:
+
+- save a script with all the procedure to build the current image (packages installed, files configured, etc)
+- backup the SDCard using minimal size, i.e. shrinking the Image file
+
+
+Reading the Image file
+~~~~~~~~~~~~~~~
+
+Shutdown the embedded computer, take the SDCard to a Linux PC computer and proceed with the following steps. 
+
+Open a Terminal instance and enter the following Linux command where the SDCard is mounted;
+
+``
+    df -h
+``
+
+
+Example:
+
+``
+ale@gaphl40:~/img$ df -h
+Filesystem                  Size  Used Avail Use% Mounted on
+udev                        7,8G     0  7,8G   0% /dev
+tmpfs                       1,6G   50M  1,6G   4% /run
+/dev/sda1                    50G   20G   28G  42% /
+tmpfs                       7,8G  3,4M  7,8G   1% /dev/shm
+tmpfs                       5,0M  4,0K  5,0M   1% /run/lock
+tmpfs                       7,8G     0  7,8G   0% /sys/fs/cgroup
+/dev/sda4                   813G  132G  640G  18% /home
+tmpfs                       1,6G  124K  1,6G   1% /run/user/1000
+/dev/sdb2                    58G  6,7G   51G  12% /media/ale/PI_ROOT
+/dev/sdb1                    63M   21M   43M  34% /media/ale/PI_BOOT
+``
+
+
+The last two are important: '/dev/sdb1' and '/dev/sdb2'
+
+
+Next we 'unmount', the Raspberry Pi SDcard:
+
+``
+    sudo umount /dev/sdb1 /dev/sdb2
+``
+
+Now we make a backup copy of the Raspberry Pi image.     
+
+``
+    sudo dcfldd if=/dev/sdb of=~/MyImage.img
+``
+
+If `dcfldd` is not installed, then install it and reexecute the last command.
+
+``
+	sudo apt-get update
+    sudo apt-get install dcfldd
+``
+
+Next we use the sync command to force a synchronise of any outstanding input or output
+
+``
+    sudo sync
+``
+
+Let's take a look at the backed up image file. The file size  should match the SDCard size.
+
+``
+    ls -lsah ~/MyImage.img
+``
+
+That's all !
+
+
+Shrinking the Image file
+~~~~~~~~~~~~~~~
+
+Let us assume the you used a 64GB SDcard to build your system. When you back it up, it will result in a 64GB image file, redardless the actual amount of space used in the SDcard. 
+It will not be possible to directly use this image file in a, for example, 16GB SDCard. Before it, you need to shirink the image file. 
+
+This process is not exactly simple. It involves several steps as described here http://www.aoakley.com/articles/2015-10-09-resizing-sd-images.php.
+Fortunalty, there are some scripts that perform these steps automatically. 
+I personaly suggest this `script <https://github.com/qrti/shrink>`. To run it you need:
+
+- A Linux PC computer or a Linux VM for windows users
+- Take the SDcard from the embedded computer and mount it on the Linux PC computer
+- download the `PiShrink script <https://github.com/Drewsif/PiShrink>` and follow the instructions  
+
+``
+wget https://raw.githubusercontent.com/Drewsif/PiShrink/master/pishrink.sh
+``
+
+
+``
+ale@gaphl40:~/img$ chmod +x ../pishrink.sh 
+ale@gaphl40:~/img$ sudo ../pishrink.sh image.img 
+[sudo] password for ale: 
+Creating new /etc/rc.local
+e2fsck 1.42.13 (17-May-2015)
+Pass 1: Checking inodes, blocks, and sizes
+Pass 2: Checking directory structure
+Pass 3: Checking directory connectivity
+Pass 4: Checking reference counts
+Pass 5: Checking group summary information
+PI_ROOT: 289654/3795104 files (0.2% non-contiguous), 2014409/15251456 blocks
+resize2fs 1.42.13 (17-May-2015)
+resize2fs 1.42.13 (17-May-2015)
+Resizing the filesystem on /dev/loop1 to 2226004 (4k) blocks.
+Begin pass 2 (max = 369264)
+Relocating blocks             XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
+Begin pass 3 (max = 466)
+Scanning inode table          XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
+Begin pass 4 (max = 22681)
+Updating inode references     XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
+The filesystem on /dev/loop1 is now 2226004 (4k) blocks long.
+
+Shrunk image.img from 59G to 8,6G
+``
+
+Generating checksum
+~~~~~~~~~~~~~~~
+
+Finally, it is recommended to generate a checksum file for the image file.
+This is usefull to check whether the file was correcpted during some data transfer. 
+
+``
+$ md5sum image.img > image.md5
+``
+
+It results in a text file like this one. Save this file with the image file.
+
+``
+$ cat image.md5 
+75e87507e672de53241df4d724a0aac4  image.img
+``