Low Power Nas New Direction: Windows Home Server

13 09 2009

The plan is to use Windows Home Server at this point. It goes against the idea of every component being as low powered as possible but right now I need/want a middle ground on this project. But like many things coming out right now the best way to save power is to turn things off when you don’t need them.  So my goal has shifted to include this as the main power saving method. Actually, that has always been a large part of the plans but for my sanity I need to suck up about 5 W.

The cons of Windows Home Server are mostly power and cost related.  The cost is about $100 for a retail copy of the product.  Power wise though spinning down disks sounds like it isn’t going to be possible.  This is where the Green Drives I’m buying are a huge boon.

The original plan was to use FreeNAS on a Solid State 512 Memory module.  I believe this model used about 0.25 W of electricity or maybe less or a bit more I’m not sure I don’t have it in front of me.  So the real differences in the WHS setup is that I can’t spin down the storage disks and the the install partition needs to be 80 GB at least…which means a HD. I can’t justify $300 for a SSD large enough for that.

So where does that leave me?  I have two options:

1) Install the the OS on the 500 GB Green drive – The down side to this is that then there is NO hope that I can spin down the storage disks at all.  And this is assuming that WHS doesn’t spin them down already past idle and into standy…but I can’t imagine it does.

2) Install it on an OS specific HD – This is my choice.  In the short run it will take a bit more power but if I can successfully spin down data disks or reduce read/writes to them it could be a savings.

To keep with my “one day we will make it into the Chenbro case” I ordered a PATA 2.5″ disk that is 160 GB.  That should be plenty for the OS, add a second level of HD redundancy with only data drive and most importantly leave open the whole 4 SATA ports for data drives in the Chenbro case. The HD according to specs uses 2.1 W at Read/Write, 0.6 W at idle, and 0.25 at standy.

Model Read/Write Idle Standby
Samsung Spinpoint M HM160HC 2.1 W 0.6 W 0.25 W
WD Caviar Green 500 GB WD5000AACS 5.4 W 2.5 W 0.46 W
Estimate of Flash IDE Module 0.5 W 0.5 W 0.5 W

So what about this energy thing? Lets look at some numbers.


Its been a few months since I started this post and actually have had the Windows Home Server up and running since mid-June I think on the downloadable demo copy.  In the next month I am going to have to buy the full copy and migrate soon.  Since I’ve been running on it I have some reviews of it but for right now lets stick with the power conversation.

There are two ways to save power: 1) reduce the amount that each device draws and 2) reduce the time that draws it.  With Windows Home Server the easiest thing for me to focus on is #2: making sure it is one when I am using it and off when I am not.  I don’t use the server as a 14/7 on box instead opting to use WOL and timed sleep modes to turn it off and on when needed.

In the 3 months I’ve had it online it has used a total of :17.81 kWh.  That’s about the same as leaving a 100 W light bulb on all day and night for a single week.   And the amount used by a CFL in a month.  So basically that comes down to being less than the 200 W the light bulbs in my room use that I only use at night  Iwould guess.  I don’t have that exact measurements but it seems it would be accurate.  Since I live in an apartment and we use electricity for heat and hot water I’d be curious how much of the energy we use is my server. 

So I’d say it is a success. I think WHS does throttle down the drives when they are not in use which is helpful.  The other part of that story is that is 17.81 with an in efficient power supply.  If I put it onto a mini-ITX powersupply I bet it would drop more because the load is always around 38W and peaks at 41W when ALL drives are spinning.  I suspect there is some power loss in conversation that I could cut out.




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