Diisk Cooling Options

[Phil Williams]

So I've got my TrueNas box running and burned in so now is time to make sure the hardware is running as expected. I see my drives running at about 33-35 degrees which is a little high for me. I have 6x WD Pro drives in a Fractal Define R6 case and there are two fans (120mm I believe) that shipped with the case at the front blowing air across. The image below shows the fan direction for each fan.

Now there aren't enough bays to checkerboard the drives so I've split them into two groups of three to take advantage of each fan. My feeling is that the fans are not up to the job. They are super quiet but I think I might need something with more oomph.

Any recommendations? I appreciate the fact the more powerful the fan then the louder it will be but I'd like to keep noise to a minimum if I can.

 

[WI_Hedgehog]

As long as cool air is moving over the drives (even slowly moving) they should stay cool. 500 RPM with a fan that can create reasonable static pressure is plenty.

To make this happen:

• the drives need to be spaced 1 cm or further apart so there's not much air resistance, alternatively the fans can be ducted to force the air between the drives.
• the air needs a directed flow path (like a fluid it takes the path of least resistance, so it has to be forced where you want it); given the wall the drives are mounted to is solid the 90° turn creates dead zones.
• plastic damps vibration though is also a thermal insulator.
• closed-bottom trays impede air flow and static air acts as an insulator due to low thermal conductivity.

In your case I'd imagine some of the air being pushed in by the front fans is being drawn out by the upper power supply, rear upper fan, rear lower fan, thereby bypassing the drives. The area containing the drives needs to have higher pressure on one side of the drives and lower pressure on the other side in order to create airflow across the drives. To do this you either need "more suck" which has some thermal advantages but is hard to create, or "more pressure" which is easier to create but wants to take the path of least resistance, or both "more pressure" and "more suck" to get the air to flow over the drives.

As a note, that large empty space between the drives adds an area of less resistance, so the drive below it should be cooled more than the others, and the others under-cooled by comparison; the system may be better served with a uniform space between the drives for the purpose of uniformly forcing the air over the drives.

 

[Phil Williams]

Thanks for the reply, good insights.

I don't think there is enough mounting points to space the drives out evenly across the rack but I will double-check. It might be that just one drive is closer then the others. I've just checked the temps on the drives and they are sitting at the the following. The temperatures relates to the drives from top to bottom:

34
36
34

35
38
37

The temps are higher than normal right now as the NAS is under load and the sun is beaming through the window warming the room ;) The bottom drives are running higher than the top group though.

I've only got the stock fans running right now with two at the front for intake to the drives and the exhaust at the top right. The PSU is located at the bottom left. The fan spec is the same for each:
1000rpm
Max air flow: 68.4CFM
Max air pressure: 0.71mm

Looking at the possible locations for fans I do have options though:

• Front fan
  3x 120 mm or 2x 140 mm (2x Dynamic X2 GP-14 included)
• Top fan
  Standard layout: 3x 120 mm or 2x 140 mm; Open layout: 3x 120/140 mm
• Rear fan
  1x 120/140 mm (1x Dynamic X2 GP-14 included)
• Bottom fan
  2x 120/140 mm

These are all the possible mounting fan points:

As I have 6 drives fitted and a DVD, the fan at the top right of this image would be a no-go although I could use 2x 140mm at the top left instead of 2x 120.

I'm thinking maybe adding the two fans at the bottom right to draw the air out and exit under the case.

 

[Davvo]

If you have a 3D printer you could make HDD trays with the bottom exposed, that would help (but requires specific knowledge and machinery).
Increase air flow, separate the trays (one slot occupied, another empty, occupied, empty, ecc...).

 

[Phil Williams]

I would love a 3D printer but I also have a wife. Hiding this monster NAS under my desk has got me out of trouble so far but adding a 3D printer to my office may take more explaining ;)

I might just go old school though and fashion some funnels for the front. No one will know they are there.

 

[artstar]

Such temperatures aren't necessarily out of the ordinary for 7200RPM, depending on the ambient temperature of the room. What is your room temperature at those drive temperatures?

For example, my room temperature is currently about 27C, with my 7200RPM drives (also WD Red Pro) running between 39C and 41C as a result, in a 1RU Supermicro chassis and fans at relatively low speed to keep noise down as a priority. Whether Seagate Ironwolf (5400RPM) or WD Red Pro (7200RPM), the drives always ran a couple degrees warmer in my old pair of Synology RS816 and RS820 units, and those drives would typically last about six years before bad sectors would appear on any of them, but that was the only issue I ever had out of past drives.

So consequently, I never worried much about the drive temperatures as a result. I don't feel the need to run the air conditioning in the room unless things get uncomfortably warm in the summer. Perhaps that's a flippant attitude for me to have but replacing a drive or two every six years is not a bad thing in my book.

 

[Phil Williams]

What is your room temperature at those drive temperatures?

Currently at 19.4 degrees. I also have the benefit of living in Scotland so cooling is not so much of an issue ;)

I may be overthinking but just from reading some of the other threads here, getting close to 40 degrees for drives is something to try an avoid. Considering the cost of these I would like to eke their life out somewhat.

 

[artstar]

Hah! If your room is that chilly, then yes, I can understand why you'd want to squeeze a better operating temperature out of them. I know I would be tempted but being born of a reptilian family, I need my room nice and warm, or I turn into a fairy princess.

 

[WI_Hedgehog]

This is total jenkiness, but...

Our 1-gallon U.S. milk jugs are made out of plastic that can be cut with scissors and formed with an industrial hand-held (hair salon) hair dryer (or preferably a heat gun). This is an affordable way to make air ducts.

Fan mounting vibration dampers pushed through the plastic and into the back side of the fan hold the air duct in place. (Your wife won't see it once you put the side panel back on.)




---
As a note, if your home projects better who you are, your earning potential, and keep you out of trouble, your spouse should consider themselves (expletive) lucky to have you. (Because there are plenty of younger women who would.)

 

[Phil Williams]

As a note, if your home projects better who you are, your earning potential, and keep you out of trouble, your spouse should consider themselves (expletive) lucky to have you. (Because there are plenty of younger women who would.)

She's actually pretty cool about it. We're both in our 50's now so she does tend to give me free rein, we have the house money, shared money and our own money. She will just roll her eyes and say "How much!"

My justification for this one is Hikvsion camera recordings being stored onto the NAS and decluttering the living room by burning across all our CDs and DVDs. A clutter-free home soothes the soul (apparently) :)