cooper Posted November 23, 2014 Share Posted November 23, 2014 (edited) I've described my current fileserver here before.In short, I went from an absolute electricity guzzler to something that takes a sip every so often.As time progressed, I started to once again get disappointed with my current setup, specifically once again the power requirements. I used to have 2 'always on' computers where 1 would act as a gateway to the internet and the other would be a fileserver. Since they're always on, I wanted to get the power draw of these devices to an absolute minimum. The current specs are:Gateway boxVia Epia-SP with a Via Eden CPU @ 800MHz1GB RAM250GB SATA HD100W PicoPSU + 150W power brickWhen Via originally came with these fanless Eden boards, I bought 4 of which 3 have succumb to the capacitor plague but this one is still going strong. The PicoPSU is rather more powerful than need be but I already had one so... Total power draw of this set is about 20W idle. It's only got 100MBit networking, but since it's my way out to the internet and I've only got 25MBit it's sufficient. When I download something using it and want to transfer it to the fileserver, it's a bit slowish, but managable.FileserverAMD A50-based MoBo with onboard AMD E-350 CPU.2GB RAM2x2TB Samsung SpinPoint + 1x3TB Western Digital + 1x16 GB Kingston SSD (slow but cheap)550W PSUI'm too lazy to open up the box to verify the board, but it's got a fan on it which is starting to get a bit noisy. Scratchy sounds. Yes, I'm certain it's that 40mm fan on the heatsink of the CPU and not the harddisks making that noise. Mainly due to the harddisks and the rather excessive PSU this thing draws about 40W idle.So this setup eats almost 1500 Watt per day doing absolutely nothing. When I made this setup, that was actually pretty damn decent. Since then though, affordable low-power ARM boards that still provide very decent performance have become widely available and have by now reached the point where they can better the above setup in interesting ways.Now then, please let me introduce you to the PcDuino3 Nano. This gorgeous little board has an AllWinner A20 CPU, 1GB RAM, 3 USB 2.0 ports (1 OTG), Gigabit ethernet and a SATA port. I've just ordered 2 for $90 including shipping - my own little christmas present to me.For the gateway box, things are fairly straightforward: I have a USB ethernet adapter for 100MBit which will go to my router. Since it's 100MBit USB 2.0 will suffice and given the fact that I only get 25 MBit off the internet it'll suffice in that regard aswell. The GBit goes to my LAN and should speed things up nicely. I'll use one of the 16GB Class 10 MicroSD cards I used for performance testing as local storage and network-mount the fileserver for the larger stuff (torrents and the like) now that the network performance should suffice.Which brings us to the fileserver which, to be honest, is going to be infinitely more interesting because the problem here is that I still want to attach multiple harddisks even though the PcDuino only has 1 SATA port. Luckily, SATA has a solution for that: Port Multiplication. Using a board such as this you can connect up to 5 harddisks to a single port. The only downside here is that the board does Command Based Switching (CBS) which basically means only 1 drive can be accessed at any given time whereas the rather more expensive FIS-based port multipliers allow you to access all devices simultaneously and you're only limited to the speed of the SATA port. However there's another problem: Port multiplier support isn't part of the standard SATA spec and many SATA controllers don't yet support it. It took some digging but today I discovered this forum post describing how a small kernel patch would enable port multiplier support on the BananaPi, another, somewhat more expensive A20-based board. That was the clincher for me: Gigabit and multiple harddisks on an ARM-based platform. Nice!Now you might ask "Where, exactly, does the 'hack' come in?" and you'd be right to ask. The point is that these ARM boards run off of 5V as does the port multiplier board. You can find solutions for cheap NAS devices based on, for instance, the Raspberry Pi but they work by using 2.5" mobile harddisks that operate on 5V and thus can be powered over USB with a little fiddling. I'll be using full 3.5" Desktop harddisks that take the vast majority of their power in using the 12V line of the SATA power plug. The solution I've come up with is to take a standard 12V power supply I already have (the one currently in the gateway box to power the PicuPSU could even be used, but it's WAY too powerful for what I need here) and the 12v to 5v buck converter I bought for my Odroid cluster project. That thing is rated for 6A. So, 12v comes in from the power brick which will be split. 12V continues to the appropriate line on a Molex connector (I have leftover Molex splitters and Molex to SATA cables) and the other end goes to the buck converter. From there, 5v goes to the appropriate line on that same Molex connector as well as to the 2 PcDuino's and the port multiplier board. The PcDuinos are each rated at 2A which might be cutting it a bit close, but if my Odroid is anything to go by, at least half of that is for when you kick the graphics on the ARM board into high gear, which I won't be doing anytime soon.My hope is that with this setup I'll have equal or, in the case of the gateway device, better performance at about 30 Watt of power draw. Given my current usage pattern for my fileserver (the girlie didn't like me removing files from there unless the movie really sucked hard - now I only keep stuff I expect to go and watch sometime soon) I expect to be able to take out the 3TB harddisk probably reducing the power draw to about 25W.Going this route will cost me about 110 dollars which at todays rates is about 90 euros. The rule of thumb here in .nl is that 1 watt of non-stop power draw for a full year will cost you 2 euro meaning that if I do manage to go from the current 80W to 30W I'll be saving 100 euro per year in electricity costs. In other words, this little project will start paying for itself in just one year. Edited November 23, 2014 by Cooper Quote Link to comment Share on other sites More sharing options...
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