Since their release I have always been interested in the Raspberry Pi single-board computer and the numerous iterations and copycats that followed. One idea I had for using them was to build a low-power Network Attached Storage (NAS) to serve as a backup solution, media sharing centre and download client. I was already familiar with the Linux packages required for this kind of setup so the big challenge was the hardware itself.
My first attempt at this was based around the original Raspberry Pi Type B board combined with a USB external hard drive. This worked well but had very slow transfer speeds due to the USB and Ethernet controllers sharing the same bus: transfer speeds never exceeded 4-5MB/s. After some research I came across a copycat board named the ‘Banana Pi’ that instead had a full 100/1000 network interface alongside a dedicated SATA port. As a bonus it also had a dual-core processor, something the original Raspberry Pi lacked.
After some testing, the prototype ‘BanaNAS’ was born. However, the setup was messy, with two power supplies required and lots of cabling loose on my desk. I then worked out a power solution that would power both the Banana Pi board and the 3.5″ hard drive from one cable. The whole setup required one 12v supply and two 5v supplies: One 5v supply is used by the Banana Pi whilst the remaining connections are both used by the hard drive. I used a spare 12v 3A laptop power supply unit as a base and split it’s output into a 12v to (2x) 5v converter, using a small transformer usually used in automotive interiors. This gave me everything I needed and it worked perfectly first time.
Since then I have installed all of the components into a mini PC case and fixed them in place with the necessary ports routed to the rear of the chassis. I have also made tweaks to the Linux operating system to improve reliability, the box has now been running constantly for over 6 months with no issues at all. The network transfer speeds are around 25-30MB/s; six times faster than the original prototype and much more usable in a day-to-day situation.