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A command to burn many SD cards for building PI clusters

Project description


cm-burn is a program to burn many SD cards for the preparation of building clusters with Raspberry Pi's. The program is developed in Python and is portable on Linux, Windows, and OSX. It allows users to create readily bootable SD cards that have the network configured, contain a public ssh key from your machine that you used to configure the cards. The unique feature is that you can burn multiple cards in a row.

A sample command invocation looks like:

cm-burn —-name  red[5-7] \
        --key ~/.ssh/ \
        —-ips 192.168.1.[5-7] \
        —-image 2018-06-27-raspbian-stretch

This command creates 3 SD cards where the hostnames red5, red6, red 7 with the network addresses,, and The public key is added to the authorized_keys file of the pi user. The password login is automatically disabled and only the ssh key authentication is enabled.


The process of the burn is as follows.

  1. start the programm with the appropriate parameters the program will ask you to place an SD Card in the SD Card writer. Place it in
  2. the specified image will be burned on the SD Card
  3. next the SD Card will be mounted by the program and the appropriate modifications will bbe conducted.
  4. after the modifications the SD Card will be unmounted
  5. you will be asked to remove the card
  6. if additional cards need to be burned, you will go to step 2.

In case a SD Card of a PI in the cluster goes bad, you can simply burn it again by providing the appropriate parameters, and just print the subset that are broken.

Setting up a Single Large Cluster with cm-burn

cm-burn will setup a simple network on all cluster nodes configured. There are different models for networking configuration we could use. However we have decided for one that allows you to interface with your local Laptop to the cluster via Wifi. The setup is illustrated in Figure Networking.

Figure: Networking

We assume that you have used cm-burn to create all SD cards for the Pi's. One of the Pi's is specially configured with the command

cm-burn --master red01

The SD Card in the SD Card writer will be configured as a master. If the name does not match it will be configured as a worker. Only the master is connected with the Wifi network. All other nodes rout the internet connection through the master node. As the master node is on the same Wifi network as the laptop you can login to the 'master' node and from there log into the workers. To simplify access you could even setup ssh tunneled connections from the Laptop via the master. But this is left up to you if you wish.

As a result you will be able to login on each of the machines and execute commands such as

sudo apt-get update

Certainly you can even have a much simpler setup by just attaching a keyboard, mouse and monitor/TV to your master. This will allow you to directly work on the master node, not needing any additional hardware.

Setting up a Cluster of Clusters with cm-burn

To integrate the clusters into a single network, we need a switch or combination of switches to which we connect the clusters. This is depicted in the Figure Cluster of Clusters

Each cluster is naemed cluster01-clusterNN. The hostnames are node followed by 3 zeros padded with the node number There is a correlation between the cluster number and the node numbers in the following interval

a cluster has the nodes

[(clustername - 1) * 5 + 1, (clustername - 1) * 5 + 5]

For convenience we will be also enabeling a cluster burn logic, that burns all images for a given cluster

cm-burn --workers=5 --name=cluster --nodes=nodes --id=3


Raspberry Pi

We assume that you have set up a raspberry pi with the newest raspbian OS. We assume that you have changed the default password and can log into the pi.

We assume you have not done anything else to the OS.

The easiest way to duplicate the SD card is simply to clone it with the build in SD Card copier. This program can be found in the menu under Accessories.

SD Card Copier

Figure: SD Card Copier

This program will copy the contents of the card plugged into the PI onto another one. The only thing you need is an USB SD Card writer. You cn accept the defaults when the cards are plugged in which allow you to copy the Internal SD Card onto the other one. Just be carefull that you do not overwrite your internal one. This feature can also be used to create backups of images that you have worked on and want to preserve.

Thus as you can see there is not much you need to do to prepare a PI to be used for burning the SD Card.

TODO: Python3

Card Burning from commandline

  • Insert card and find mmcblk0, e.g. no letter p in it for partition

sudo ls -ltr /dev/*

sudo dd bs=1M if=~/.cloudmesh/images/imagename.img of=mmcblk0 status=progress conv=fsync


Card Burning

On OSX a good program is to use etcher for burning the images on disk:

To access it form the commandline you can also use

File System Management

Unfortunately, the free versions of writing the ext file system are no longer supported on OSX. This means that as of writing of this document the best solution we found is to purchase and install extFS on the MacOS computer you use for burning the SD Cards. If you find an alternative, please let us know. (We tested ext4fuse, which unfortunately only supports read access, see Appendix)

To easily read and write ext file systems, please install extFS which can be downloaded from

The purchase price of the software is $39.95.

If you like to not spend any money we recommend that you conduct the burning on a raspberry pi.

TODO: PYTHON3 use pyenv

Tip: An alternative would be using virtualbox and using a virtual machine to avoid purchasing extFS.


Elevate permissions for Python.exe in Windows

  • Create a shortcut for python.exe
  • Change the shortcut target into something like C:\xxx...\python.exe
  • Click "advance..." in the property panel of the shortcut, and click the option "run as administrator"

Executable needed to burn the image on SD Card:

Download CommandLineDiskImager from the following url

The above executable will be used by cm-burn script.

It's necessary to burn the raspbian image to the SD card with this executable manually or thru Etcher in order to continue with next step.

CommandLineDiskImager.exe C:\Users\John\Downloads\raspbian.img G

File System Management

Download the Open source ext3/4 file system driver for Windows installer from

  • Open Ext2fsd exe
  • The burned image in the previous step in SD card will have 2 partition
  • FAT32 partition will be assigned with the Drive letter - Boot Drive
  • Assign Drive Letter for EXT4 (Right click on the EXT4, Assign letter.
    The drive letter will be used while running cm-burn) - Root Drive
  • Setting Automount of this EXT4
  • F3 or Tools->Ext2 Volume Management
  • Check-> Automatically mount via Ext2Mgr
  • The instructions above needed for the Ext2fsd to reserve the Drive Letters and any raspbian image burned to SD will be auto mounted to the specific reserved drive letters. These drive letters need to be specified while using cm-burn


Install on your OS

Once you have decided which Computer system (MacOS, Linux, or Windows) you like to use for using the cm-burn program you need to install it. The program is written in python3 which we assume you have installed and is your default python in your terminal.

To install cm-burn, please execute

git clone
cd cm-burn
pip install .

In future it will also be hosted on pypi and you will be able to install it with

pip install git+

To check if the program works please issue the command

cm-burn check install

It will check if you have installed all prerequisites and are able to run the command as on some OSes you must be in the sudo list to runi it and access the SD card burner as well as mounting some file systems.



       image: None

Manual page

  1. git clone
  2. cd cm-burn
  3. python install
  4. Copy the Raspberyy PI images to be burned under ~/.cloudmesh/images

The manual page is as follows:

cm-burn -h
Cloudmesh Raspberry Pi Mass Image Burner.

  cm-burn create --group GROUP --names HOSTS --image IMAGE [--key=KEY]  [--ips=IPS]
  cm-burn gregor --group GROUP --names HOSTS --image IMAGE [--key=KEY]  [--ips=IPS]
  cm-burn ls
  cm-burn rm IMAGE
  cm-burn get [URL]
  cm-burn update
  cm-burn check install
  cm-burn (-h | --help)
  cm-burn --version

  -h --help     Show this screen.
  --version     Show version.
  --key=KEY     the path of the public key [default: ~/.ssh/].
  --ips=IPS     th ips in hostlist format

Location of the images to be stored for reuse:


  cm-burn create [--image=IMAGE] [--group=GROUP] [--names=HOSTS]
                 [--ips=IPS] [--key=PUBLICKEY] [--ssid=SSID] [--psk=PSK]
                 [--bootdrive=BOOTDRIVE] [--rootdrive=ROOTDRIVE]
                 [-n --dry-run] [-i --interactive]
  cm-burn ls [-ni]
  cm-burn rm IMAGE [-ni]
  cm-burn get [URL]
  cm-burn update
  cm-burn check install
  cm-burn hostname [HOSTNAME] [-ni]
  cm-burn ssh [PUBLICKEY] [-ni]
  cm-burn ip IPADDRESS [--domain=DOMAIN] [-ni]
  cm-burn wifi SSID [PASSWD] [-ni]
  cm-burn info [-ni]
  cm-burn image [--image=IMAGE] [--device=DEVICE]
  cm-burn (-h | --help)
  cm-burn --version

  -h --help         Show this screen.
  -n --dry-run      Show output of commands but don't execute them
  -i --interactive  Confirm each change before doing it
  --version         Show version.
  --key=KEY         the path of the public key [default: ~/.ssh/].
  --ips=IPS         the IPs in hostlist format
  --image=IMAGE     the image to be burned [default: 2018-06-27-raspbian-stretch.img].

  cm-burn create --names red[000-010] ips --image rasbian_latest
  cmb-urn create --group g1 --names red[001-003] --key c:/users/<user>/.ssh/ --image 2018-06-27-raspbian-stretch.img --bootdrive I --rootdrive G --domain --ip 192.168.1.[111-113]


OSX ext4fuse

Unfortunately ext4fuse only supports read access. To install it please use the following steps. However it will not allow you to use the cm-burn program. It may be useful for inspection of SD Cards

On OSX you will need brew and install osxfuse and ext4fuse

brew cask install osxfuse
brew install ext4fuse

To run it, your account must be in the sudoers list. Than you can do the following

mkdir linux
mkdir boot
cp  ../*.img 00.img
brew cask install osxfuse
brew install ext4fuse
hdiutil mount 00.img 

This will return

/dev/disk3          	FDisk_partition_scheme         	
/dev/disk3s1        	Windows_FAT_32                 	/Volumes/boot
/dev/disk3s2        	Linux          

We can now access the boot partition with

ls /Volumes/boot/

This partition is writable as it is not in ext format.

However to access the Linux partition in read only form we need to mount it with fuse

sudo mkdir /Volumes/Linux
sudo ext4fuse /dev/disk2s2 /Volumes/Linux -o allow_other
ext4fuse /dev/disk2s2 linux
less linux/etc/hosts
sudo umount /Volumes/Linux 

Activate SSH

see method 3 in


Set up ssh key on windows (use and document the ubuntu on windows thing)

you will have ~/.ssh/ and ~/.ssh/id_rsa

copy the content of the file ~/.ssh/ into ???/.ssh/authorized_keys ??? is the location of the admin user i think the username is pi

enable ssh on the other partition while creating the fike to activate ssh


change /etc/hostname

Activate Network


Change default password

From the net (wrong method):

Mount the SD card, go into the file system, and edit /etc/passwd. Find the line starting with "pi" that begins like this:


Get rid of the x; leave the colons on either side. This will eliminate the need for a password.

You probably then want to create a new password by using the passwd command after you log in.

The right thing to do is to create a new hash and store it in place of x. not yet sure how that can be done a previous student from the class may have been aboe to do that Bertholt is firstname.

could this work?

python3 -c "from getpass import getpass; from crypt import *; p=getpass(); print('\n'+crypt(p, METHOD_SHA512)) if p==getpass('Please repeat: ') else print('\nFailed repeating.')"

Unmount Drives on Windows

RemoveDrive.exe needs to be downloaded to c:\Tools from the following path and to have the Administrator rights (Right Click on the exe -> Properties -> Compatibility Tab -> Run this program as an Administrator

See also

Gregor thinks that unmounting is much easier in an aelevated command prompt using

mountvol <Drive Letter>: /d


OSX during burning

/dev/disk0 (internal):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                         2.0 TB     disk0
   1:                        EFI EFI                     314.6 MB   disk0s1
   2:                 Apple_APFS Container disk1         2.0 TB     disk0s2

/dev/disk1 (synthesized):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      APFS Container Scheme -                      +2.0 TB     disk1
                                 Physical Store disk0s2
   1:                APFS Volume Macintosh HD            811.4 GB   disk1s1
   2:                APFS Volume Preboot                 26.8 MB    disk1s2
   3:                APFS Volume Recovery                519.0 MB   disk1s3
   4:                APFS Volume VM                      9.7 GB     disk1s4

/dev/disk2 (external, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:     FDisk_partition_scheme                        *31.9 GB    disk2

/dev/disk3 (external, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:     FDisk_partition_scheme                        *31.9 GB    disk3

Experiment DIY multiSDCard writer

We intend to experiment to build a multiSD card writer via USB. We will attempt to do this for OSX initially, therefore we like to order the following product

We will use multiple USB card readers (possibly just USB2 till we replacethem with USB3)

Than we will rewrite our program to attempt using the SDcard writers

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