TechFindings

The Raspberry Pi has been around for some years now and it has been used in unbelievable projects. As a budget desktop computer it has not quite had the required performance (although v2 and v3 are much improving the situation over v1). However, for simple hobby server tasks the RPi can work very well.

A simple RPi (any version) setup typically requires:

• RPi
• SD Card
• USB PSU + USB cable
• Network Cable
• External USB Drive + USB Cable (+power adapter)
• A case

That is without display, mouse and keyboard, and you dont have a power button. It gets a bit messy.

The market is full of RPi cases that all do the same thing: nothing. They just contain the board. The market is full of mini/micro-towers for MiniITX. There are rather expensive NAS devices that come without hard drives. Why are there no small tower cases that comes with:

• PSU
• Slots for 1-2 hard drives (+USB to SATA converters)
• Cabling that makes everything tidy and neat

Powering the RPi using an external hard drive
I happened to have an external USB drive with an integrated USB hub (an Iomega Minimax that was left alone when its Mac Mini died). With some wood and glue I built a simple stand for the hard drive and the RPi:

As you can see:

• the hard drive powers the RPi, and I can even use the hard drive power switch
• the Ethernet and USB ports are conveniently available on the back side
• the footprint is just slightly larger (just taller) than the hard drive itself
• the two USB cables between RPi and harddrive are nicely contained
• heat/ventilation should be pretty good

I have experienced no problems powering the RPi from a USB drive that it itself is connected to. It may not be a supported or recommended configuration, but for practical purposes it works for me.

Performance
I mostly run Syncthing on this RPi. The bottleneck is very much the 700MHz ARMv6 CPU, not the USB2-to-SATA-overhead.

hdparm gives me:

$ sudo /sbin/hdparm -t /dev/sda
/dev/sda:
 Timing buffered disk reads:  82 MB in  3.03 seconds =  27.09 MB/sec

$ sudo /sbin/hdparm -T /dev/sda
/dev/sda:
 Timing cached reads:   496 MB in  2.01 seconds = 247.36 MB/sec

Of course it sucks compared to what you can get in 2016, but it is not remarkably bad in anyway. And it is not so fun to live on an SD card.

The Western Digital Kit
The other day Western Digital announced both a special 314GB hard drive and accessories to make it all nice.

Plusberry Pi
There is also the interesting Plusberry Pi project.

Picocluster
Picocluster is clearly bringing new options! Not so much focus on support for a USB Hard Drive though. Some models have an HDMI port. I am not sure, but I think the idea is that you connect one RPi to the external USB/HDMI ports, and then that RPi can control the other one, if you run Picoclusters custom distribution. Not so bad, but not a KVM either. Perhaps a little modification to make a serial switch so RPi #2-5 can be controlled from #1 over serial?