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[8vgumby]

I wanted to share something with the community that is probably not suggested by D-Link.  

I keep my unit oriented horizontally, so the rubber feet are doing diddly.  I am doing this for space requirements, but noticed there was an inherent vibration that existed seemingly from the hard drive not being anchored by anything other than the SATA connector.

I was able to press a toothpick down into both sides of the narrow-side of each hard drive, effectively wedging them into place against the frame of the DNS-320.  When this is done the hard drives no longer wiggle.   I then placed the entire unit (still horizontal) on a felt pad.  

Vibrations are gone, and the device is significantly quieter.  To put this into context, the device lives next to a PS3 and you could clearly hear the device over the PS3 which is a fairly loud device to start with (relatively speaking).  Now when the PS3 is running, you cannot hear the DNS-320.

Just to be clear, I am not suggesting the HDD is vibrating on it's own accord - that would go right back in a box to Western Digital.  I believe a resonance exists between the two spinning drives and the fan pulsing on/off which causes the entire assembly to vibrate at some frequency thus causing the drives to vibrate within the frame.  Future revisions/designs need damping material or a better fixture method.

[albert]

It's not true that the HDD is anchored by the Sata connector which is likely to break if place horizontally. There are metal "hook" on the side that guide and support the drive into place.

There are foam pad on the NAS cover that help to further hold the drive and keep vibration down but unfortunately it's not available on every batch.

[8vgumby]

No where did I mention that the orientation would break the connector.  That is not what I was suggesting, and is misleading to anyone reading this post.

There are in fact metal hooks that guide and support the drive.  Then once the dive is settled, there are zero bolts/screws to anchor the drive, so despite all best efforts, your index finger can jiggle the drive a fraction of an inch in any direction.  When I close the lid on my device, holding it with the power off, I can physically feel the drive shifting as I re-orient the drive from horizontal to vertical and back again.  It's not sliding "all over", but you can hear it moving a bit as it clearly isn't anchored to anything (in the classical sense of using a bolt to restrain motion), obviously it is limited by the guides and hooks, or reorienting would be a disaster as the drive would slam around and break the connector.

However, the fact that all it uses are those guides, you can jiggle it which leads to vibrations that are then driven by the external fan to a mode of resonance during operation.  Additionally, there is no foam in my lid just a hollow plastic and metal cavity - perfect for vibrating.

http://en.wikipedia.org/wiki/Normal_modes

[albert]

No, you didn't mention that but you did and I quote "I am doing this for space requirements, but noticed there was an inherent vibration that existed seemingly from the hard drive not being anchored by anything other than the SATA connector" in your first post which is misleading.

This NAS model is design for vertical drive placement and easy removal, having to secure the drive(s) with bolts/screws clearly defeat the intended purpose. D-Link should have opted for a quieter fan instead and ensure that every batch come with foam pad on the cover.

[nmcar]

I do not remember whether my NAS had that piece of foam in the cover (I will check), but I suffer the device noise. According to the picture posted by Albert, I guess it would not be difficult to stick a piece of foam to the cover. Would that help in reducing the noise? Is it worth the effort?

[nmcar]

Albert: does your NAS emit an annoying noise? Mine does when it runs at high speed, which is almost all the time (I set the fan at Auto speed). Or is it barely noticeable with the foam?  How thick is the foam approximately?

[albert]

The only noise for my set come from the cooling fan which is kind of ignoring when it ran at high speed. The foam help to secure the drive(s) firmly in place and keep vibration down, not sure if it made a different since my came with it.

You can try turning off the fan off and see if that the cause, the drive itself even if running at 7200RPM (my has both 5400 and 7200RPM) shouldn't generate much noise.

The foam thickness is about 8mm.