Mirra Mirra in the Closet

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THE INTERNALS

The actual device size is similar to a small form factor computer. It is apparent that Seagate did not design this specifically for the Mirra, but instead purchased it from an OEM. There is a masked 5.25" drive bay and front USB ports, with no real use for either. The dimensions are 12" tall, 5" wide, and 10" deep, and it weighs about 6 lbs. There are feet on the bottom and both the side panels allowing the Mirra to sit vertically or horizontally.


Mirra sitting horizontally with the drive bay exposed.


Mostly non-functioning ports on the back panel.

On the rear panel there are two USB ports, composite video, s-video, and standard audio connectors (line in/out and microphone), although none of these worked. It appears the Mirra's operating system has disabled access to the motherboards I/O functionality. There are also LPT, VGA, and serial ports connectors blocked by rigid plastic covers. A little prying was all it took to remove these, and with a monitor connected to the Mirra, the Linux boot sequence could be seen.


Mirra uses a Debian Linux operating system.

Opening the device shows that the heart of the Mirra is a VIA EPIA ESP5000 mini-ITX computer. VIA is known for its low power processors and integrated single board computers. VIA's website states the ESP processor version used in the Mirra as being "ideal for fanless systems with power sensitive requirements". The VIA ESP processor datasheet shows that it runs at 500MHz, has a core voltage of 1.2V, and a maximum power dissipation of 5W. Potentially this means that the Mirra could be very low noise (limited only by the HDD), but we will have to wait until testing to hear the end results. The last item of note on the motherboard is a single 64MB SDRAM DIMM.


Mirra sitting vertically with the drive bay exposed.

The next two main sources of noise are the power supply and hard disk drive. The power supply is supplied by FSP group. FSP group is a Chinese power supply manufacturer that sells both OEM and retail PSU's, including one model on the Recommended PSU list at the time of this writing (FSP Green PS). The FSP150-5PL model included in the Mirra has a "Noise Killer" label on it which implies a fan controller is included in the design. However, the benefits of this may be hindered by the single 4cm fan cooling the PSU. Unfortunately, multiple screws kept us from determining exactly which model fan was used, but either way, the fan will most likely spin at very high speeds.


The source of the PSU is obvious.

Finally, the hard disk drive included in the Mirra is Seagate's 7200.8 250GB model. Seagate used to be a champion of HDD acoustics; the Barracuda IV, now long out of production, still remains one of the quietest drives ever. These days Seagate is more focused on performance and their products have dropped off our recommended quiet 3.5" HDD list altogether. Seagate states that the 7200.8 has "whisper-quiet acoustics", but based on the information below, this isn't the quietest drive. The drives that are currently tops for low noise have sound power ratings closer to 2.5 bels in idle and under 3.0 bels in seek.

Acoustic for Seagate 7200.8 (from Seagate's website)
Idle (bels-sound power)
2.8
Quiet Seek (bels-sound power)
3.2
Performance Seek (bels-sound power)
3.7



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