NAS: DS213+ & WD20NPVT – 2. Power Consumption

As announced in the first post about the Synology DS213+ and the Western Digital WD20NPVT, here’s the measured power consumption of the NAS and the two hard disks in differnt operational modes.

Measured values

The following table compares the values measured to the values as specified in DS213+’s specification.

Operational Mode	Mean power consumption (measured)	Power consumption (specification)
Off	~1W	–
System hibernation	2.9W	2.64W
on – HDD hibernation	9.6W	10.08W
on – idle	12.56W	–
on – download	13.94W	22.20W (“access”)
on – upload	15.47W	22.20W (“access”)

The spec mentions higher values for “access” and, HDD hibernation probably because they used 3.5″ HDDs. However, the value for hibernation is lower. Maybe that’s due to the measurement accuracy.

Note: The power consumed by the power supply when the device is off, is below the effective power range of the measurement device. Therefore the measured value is only an approximate value.

Measurement

For measurement, an Energy Logger 4000 device was used. It is not the most accurate one (5 – 3500 W (± 1% + 1 count), 2 -5 W (± 5% + 1 count), < 2 W (±15% + 1 count)), especially in the lowest measurement range. Still, the values measured should povide an impression of the power consumption in the different operational modes of the NAS.

For off, system hibernation, HDD hibernation and idle the power consumption is an arithmetic mean over several hours.

The download and upload, values have been measured while reading/writing a 50GB file. The values bellow are mean values over the process of reading or writing, respectively. The data rates measured during this process will be published in the next post.

Surprisingly, there is no (measurable) difference in hibernation whether Wake On LAN (WOL) is on or off. That’s why there is only one system hibernation mode.

Conclusion

15.5W at max, is not so bad for a device running two hard drives. It’s idle consumption of about 12.6W still is about twice the power consumption of other devices running 24/7 (like routers).

That’s where the the system hibernation mode comes in handy. 3W in hibernation – that’s about as much as the power supply of an old desktop light consumes when the lights are off. If you use your NAS as a private storage, or even a web server that’s a very good compromise. Of course, it would be even more economical to switch the NAS completely off, when not in use. But probably not what these devices are intended for.

Thanks to the WOL functionality, you can use a hibernating NAS almost as comfortable as if it ran all day: For usage at home, the NAS can be switched on by sending a WOL package to the NAS MAC/IP address from any PC (e.g. WOL for Windows) or mobile device (e.g. Wake On Lan for android). Actually, I don’t have to do this very often as it seems that my Windows Explorer switches on the NAS as soon as it is started, for I have mounted some NAS folders as network drives.

If you want to use the NAS as a web server you can configure your router to send a WOL package to the NAS when a request is received on a certain port, for example via HTTP or HTTPs. This will switch on the device, which takes about 30 seconds, that is, the website is delivered some seconds later, once the NAS is awake. I think in private usage scenarios this should not be too much of a drawback but it safes 75% of energy.

Doing so, allows for having a NAS or even a self-hosted web server/”personal cloud” that consumes almost no energy when it is not in use. A good enough solution for my “green conscience”, at last.

By the way, a device consuming 3W consumes about 26kWh in a year, which is about 7€ (as of 2012 in Germany, the average price for electricity was 0,26€ per kWh). In comparison: A device consuming 12.6W, consumes about 110kWh a year, which is about 29€.

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