DaveNAS / OpenMediaVault

I needed to replace my ageing NAS with something a little more modern and hackable. My old system was born out of need – I built something from parts I had lying around – an old laptop running NAS4FREE and a few external drives for data. I spent nothing but a little time.

It was clunky and slow, but very reliable. Only ageing disks and power outages beyond the UPS capacity tripped it up.

I don’t need super speed (i’m not editing videos over the network – yet) and massive capacity to just do a bit of CAD and some basic design work. I just need to store a few 100s of Gb of data, and get it backed up.

3-2-1 Backup

The tried and trusted scheme – three data copies, two media types, and one offsite copy. I built a primary NAS device, which was mounted by a secondary machine. This second machine runs Code42 (formerly CrashPlan) which uploads the data to the cloud. It also runs a copy job, on schedule which makes a duplicate of the main NAS, to another external drive. In addition, I run backintime which creates hourly, daily and weekly snapshots of the data using rsync.

The snapshots and NAS copy are exported via network shares, so if the main NAS goes down, or I need an old version of a file, I can just reach in and grab it. Easy. Total cost – zero.

The Plan

There are lots of hardware options for building a NAS of varying cost and performance. I don’t need immense speed, vast storage size nor fancy data de-duplication. I just need a few disks hanging on a node, presenting some SMB and NFS shares.

The Raspberry Pi is pretty ubiquitous these days. It isn’t particularly fast, on any measure, but the latest, at the time of writing is the Pi4 B+ It has perfectly adequate performance for my needs, its easy to source and infinitely hackable.

I bought a USB3.0-to-SATA active cable, and a 150Gb or so SSD from Crucial. I threw the latest Raspbian Buster Lite onto a micro SD card, and used the OpenMediavault 5.5.3 installer script like this:

wget -O - https://github.com/OpenMediaVault-Plugin-Developers/installScript/raw/master/install | sudo bash

After a bunch of restarts, it was possible to connect to the admin console by simply pointing a browser at the PI’s IP address.

The attached SSD was discovered in the OMV disk configurator and easily setup to provide a share which could be seen by my various devices over the network.


I had an old 19″ enclosure, with a 5V mains PSU left over from stripping down an old 10Mbit netgear switch. Since the UK was (and currently still is) on Covid-19 lockdown, I was trying to use what I had to hand. Accessing my local Makerspace was also out of the question, so I had to make do with basic hand tools, some plastic sheets and a few power tools.

What follows is a pretty crude build.

19″ case with internal mounting posts shown
Simple wiring changes to connect the fan and a USB-C connector

A simple approach would be to make an adaptor plate to screw down to those mounting posts, with holes appropriate for the Pi4 and the SSD. Normally, I would reach for the laser cutter at this point, but like I said earlier, no Makerspace access, so I needed to either do it by hand, or use a 3D printer I had in my workshop.

So, in the absence of a mechanical drawing of the case, I simply started measuring from point to point. Using FreeCAD, it was pretty straightforward to draw a sketch the required outline and get it fully constrained to fit plastic where I needed it.

It was crude, but I decided the easiest way to locate the centres of the mounting points, was to draw circles in the approximate locations, then measured between lots of nearby posts, in a kind of big triangulated mesh. With enough point-to-point measurements, the sketch was constrained.

Crude measurements (not all shown), but do enough and the sketch can be constrained

Cutouts were added to reduce material from where it isn’t needed to save print time. Once the sketch was constrained, I simply added a ‘pad’ to it, to extrude it into a 3D shape suitable for exporting as an STL for printing.

Finished mounting plate ready for printing

Next I simply attached the PI and drive:

Quick test assembly, showing the SSD1306 OLED. More about that in a bit

Status Display

I wanted to add a small display to the front to show some basic configuration and status information. So, I added a BigRedButton™ to allow issuing of simple commands to allow shutting down and rebooting of the box, in case the network goes down and I can’t connect to it.

I had a tiny OLED display in my pile of optoelectronics spares, a SSD1306. This is sold widely on eBay. It is connected via I2C and will wire direct to the Pi with just four wires. Software support was via an old python library courtesy of Adafruit:

sudo pip3 install adafruit-circuitpython-ssd1306

A common way to draw on these displays is to use the python PIL library to draw onto an internal image buffer, then when you’re finished, the buffer is pushed out on the OLED display using whatever interface connects it:

Aside: The U8g2lib library is available for Arduino users, if that floats your boat. ⛵

The button was simply wired to the nearest spare GPIO, to pulldown to ground. The GPIO was programmed to be input mode, with the pull-up enabled:

Data were gathered using a few python modules designed for extracting information from the running system, specifically psutil, and Vcgencmd:

The remaining data were gathered by extracting the output of various command line utilities:

Finally, it was necessary to register a system service, using a service file and a few commands:

This file was copied to /etc/systemd/system, then started with:

sudo systemctl start myscript.service

Finally, once it was tested, it was enabled to run on boot:

sudo systemctl enable myscript.service

This was pretty much all I did to get the thing up and running, in a case and ready to bolt into my 19″ cabinet. All I need to do is finish that project…

Testing and Deployment

The NAS has been recently switched over to be my primary, after a period of stress testing. Stability is very good, but performance is not terribly great, as is to be expected from the hardware. For running my small business and keeping my projects going, it is just fine.

DaveNAS connected for testing, until I finish my cabinet build