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Big Data, Hadoop, NumPy, R cluster computing etc. are pretty hot topics. To get my hands on them and get a deeper understanding I have decided to build my own cluster out of small Raspberry Pi 2 computers. I am not the first one to come up with this idea, you can find a few nice examples online.

I have decided to use five Raspberry Pi 2 and one Banana Pi in this cluster. The Banana Pi has the advantage of being equipped with a Serial ATA port, my plan is to use it to store the data the Raspberries are working on.

The general setup is the following:

1. 5 x Raspberry Pi 2 from Pollin for 37.95 Euro each
2. A TP-Link 8-Port Gigabit Switch for 20.99 Euro
3. a 6-Port RAVpower USB power source (3 x 1.0 Amp, 3 x 2.4 Amp) for 17.99 Euro
4. a couple of five micro USB cables for 12.99 Euro
5. Identical 16 GB micro-SD cards from Sandisk, Class 10 for 10.99 each
6. the Banana Pi (I got mine from notebooksbilliger.de for 33.89 Euro)
7. a SATA Power/Data cable to connect a 2.5″ harddisk to the Banana Pi

So altogether I spent around 320 for the electronic parts, some other parts (like SD card and USB cable for the Banana Pi) I had in my stash.

In the next article of this series I’ll describe the case I am currently building out of Lego Technics parts…

Just putting 6 microcontrollers on the table won’t work long (low WAF) so I decided to use the vast amount of my Lego Technic components to build a suitable case. In the future I might switch to a custom-made Acryl case (I could use the Dingfabrik’s laser cutter) but for quick prototyping nothing beats LEGO. For this project I had to buy a few extra components, among them two dozen LEGO 55615 which drove the costs a little.

Since the case is pretty much complete now, it is time to take a look at the software. I finally decided to run Raspian on the PIs and Lubuntu on the Banana Pi. While there may be other (maybe even more suitable) OSes available I think is the best starting point for my project. The Banana Pi is equipped with Lubuntu.

After booting the Banana Pi I switched to the German keyboard layout (unfortunately the corresponding GUI is horrible). Afterwards the usual apt-get update and apt-get upgrade took care of software updates.

The next steps are the configuration of a static IP as well as the installation of the SSH demon and samba.

EDIT

I just learnt about Bananian which is based on Debian 7. It does not provide a desktop environment, so a 2 GB SD card is said to be sufficient. Since I just want the Bananapi to act as samba server all the Lubuntu features are pretty irrelevant for me.

It also has a sshd running

Configuring the samba server and having it use the attached 2,5″ HDD was actually pretty easy.

Step 1: Mounting the harddisk

From http://mein.homelinux.com/wiki/linux/mounten I learnt how to add the attached harddisk to the fstab. blkid gave me the UUID of the disk (which I had previously partioned and formated with gparted), so I just had to a) create a directory /media/storage, b) set the access rights with chmod 777 /media/storage and add the following line to the fstab:

UUID=b06c9eb6-7cc3-429b-9176-44896e712319 /media/storage ext4 auto,defaults 0 2

Step 2: Installing samba

sudo apt-get install samba installed samba, but not smbpasswd. A quick sudo apt-get install samba-common-bin fixed this.

After I had created a „bananapi“ user on the machine I added this account to the list of samba users with the command smbpasswd -a bananapi. I then took the sample configuration for the /etc/samba/smb.conf from https://www.thomas-krenn.com/de/wiki/Einfache_Samba_Freigabe_unter_Debian and rebooted the machine.

From my Windows machine I can connect now to \\bananapiip\public and use it as a samba server. When copying a 1 GB iso image to the \public share I got an avaerage of 35 MB per second.

Remarks 2020-06-06:

[global]
workgroup = smb
security = user
map to guest = Bad Password

[homes]
comment = Home Directories
browsable = no
read only = no
create mode = 0750

[public]
# chmod -R 777 /home/uwe makes it publicly accessible
path = /home/uwe/
public = yes
writable = yes
comment = smb share
printable = no
guest ok = yes

For months it has been quiet on this front, recently I have started again my efforts to have a working cluster of Raspberry PIs. I purchased a few Pi 3 (Cyberport offered them for 29,95 Euro a piece), a Logitech 8-port hub (from Pollin, around 10 Euro) that works with 5V and therefore should work by USB power. Right now I built the stack of PIs (4 Pi 2, 4 Pi 3) by connecting all of them using M2.5 nylon spacers from Banggood. As power supply I am using an Aukey PA-T8 USB charger with 10 3.0 USB ports that deliver 70W in total.