Cooling question

[KMR]

I am going to be adding four more drives to my FreeNAS box as a RAID 10 pool and am concerned about cooling. Currently the box has 6 drives in an IStarUSA D-416 case; they are all spaced evenly apart with space for a hard drive between each drive. This arrangement keeps the drives at acceptable temperatures with the front face open (30 - 33C idle and 35 - 37C under load) but it is starting to get warmer here and I'm concerned that adding 4 drives in the free spaces will really bring the temps up. This will mean that there will be 5 drives packed directly together on each side.

The cooling in these cases isn't great but I was able to zip tie 120mm cheapo Coolermaster fans directly in front of both stacks of hard drives which is how I was able to get the reasonable temps I have now. I have toyed with the idea of making a custom fan back plane and adding some real fans but I was wondering if anyone has some recommendations on fans that I might be able to drop in as direct replacements for the current 120mm ones. I will drop the new drives in and see what happens to the temps under different scenarios and report back but I don't imagine i will be able to get away with my current setup. Any recommendations would be most welcome.

Link to the case: http://www.istarusa.com/istarusa/pr...sub=D VALUE&model=D-416&factor=4#.UcMKnZzosa4

 

[jgreco]

How are the drives mounted? In a rackmount case, you have some of the best AND some of the worst opportunities for cooling options/disasters. Since mention of any is conspicuously absent, I suspect you've done without the formality of a 5-in-3 mobile rack. Supermicro makes the nice CSE-M35T-1B which is among the more expensive options, but includes a fan with a fan failure alarm. This is not an endorsement of that product, but it is an endorsement of a fan plus failure alarm, and my guess is that it's a decent Supermicro fan with some decent stats behind it. In any situation with closely-packed components, the static pressure is a significant consideration because you need to force the air to move through millimeter-thin gaps. You can of course replicate this without the expense of a mobile rack, but sometimes it is worth paying a little money to someone who has actually engineered a solution to the problem.

 

[KMR]

I have looked at those 5 in 3 options but was unsure how effective they would be. Are these enclosures designed to increase static pressure to cool the drives effectively? I will spend the money if I need to but if I am able to avoid it that would be better for me. A piece of sheet metal would be pretty easy to fold into a fan back place.. would that give me the necessary static pressure to cool the drives?

As always, thanks for your input!

 

[jgreco]

As with most things, there's more than one way to do it. The 5-in-3's are a prebuilt fix... but not all of them even have fans. The important bits are a good fan (read: sufficient static pressure etc) and proper gapping/airflow.

 

[KMR]

Currently the drives are mounted with 5.25 to 3.5" hard drive adapters that gives them plenty of room on all sides. I checked out the SM cages and they are actually the cheapest to obtain here in Canada, which is odd but good to know because if I have to go that route I know I can get quality. That being said they will still cost me almost $300 for a pair of them which is more than I wanted to spend. Obviously if it is the only way then I'll do it, but I would rather avoid it if possible. I think for now what I'll do is mount all of the hard drives without connecting the four new ones to see what the added airflow restriction does to temperatures; hopefully that will give me some idea of what I'm in for. I'll also see if I can find a scrap piece of sheet metal to fit (hammer) in there. I remember you posting that delta made good fans, should I look at, say, 3x 120mm delta's if I go the fan back place route?
I still have a little bit of time because I'm waiting for the M1015 to arrive.

Thanks,

 

[paleoN]

Related thread with broken formatting.

 

[jgreco]

Due to the physics of it all, smaller fans often offer higher static pressure. You'll tend to find better options at 80mm than 120mm. Pressure requires work, which is basically watts.

Pressure is successfully created when air is forced to move. This is more or less controlled by the size and design of the fan blade; to successfully force air you need large fan blades. Ever seen an Archimedes' screw in action? By more fully enclosing the volume the energy is more successfully turned into meaningful work.

So look at something like the Noctua NF-S12A.

Generally a well-thought-of fan, it's a 1200 RPM 25mm thick unit that moves about 63CFM at a whopping 1.2mmH2O, using about 1.5 watts of power to do so. Look, you can see the blades really don't obstruct your view through the fan

Moving up to something like the Nidec D1225C12BBAP-31.

Now 5400 RPM, 150CFM, 15.3mmH2O, 14 watts.

As they get thicker, like the 38mm Nidec G1238B12BBZP-00:

Up to 6300 RPM, 261CFM, 53mmH2O, 53 watts.

Notice how mmH2O scales apx 1:1 with watts for these 120mm fans? (almost interchangeable!) The 120mm's also get really expensive really quickly.

So the thing is, you just don't need a high volume of air ... but you do need to force some air to move. So the most practical thing to do is to see what other mfrs are using for system builds, and then buy those fans, since they're likely to be more readily available and less expensive anyways. Numbers for 80mm posted in paleoN's "related broken thread"

 

[KMR]

Very interesting stuff. Thanks again for your replies. I have ordered a Norco 120mm fan wall in the hopes that it will mostly be a drop in part for my case. Unfortunately the 80mm fan walls only come with one of their cases. I will do some checking around on the 120mm fans and see what I can find.

The other thing I have been wondering about is restricting the air flow across the front of the case such that air is forced to flow directly over the hard drives. So, for example, the hard drives take up about 2/3 of the available space in the front of this case with the other 1/3 being open. This fan wall would pull the most air through that 1/3 because it offers the path of least resistance, so would it be beneficial to block that 1/3 of space to force the air over the hard drives? This of course would require proper fan selection as higher pressure would be necessary due to more obstructions.

 

[KMR]

I found Delta AFB1212HHE 120MM fan that seems like it will do the trick for me. 130CFM, 11.48mmH2O, 47DBa, 3500RPM. I'm a little concerned these things will wake the dead when three of them are running though. My mother board does have quite a few fan headers, but will I have problems with these fans drawing too much power? There are also two 60mm fans mounted to the rear of the case.

Thanks,

 

[jgreco]

With the advent of PWM-controlled fans, many mainboards these days no longer vary the voltage to the fans to control the speed; I'm pretty sure that this is true on the X9SCL and that the power is just wired straight through to the fan headers from the power supply. You could probably draw quite a bit of power. Looks like that fan is about half an amp. I would not expect that to be problematic as Supermicro's fans typically draw more than that.

 

[cyberjock]

Oh KMR.. I remember you because you asked about the 80mm plate in the other thread. I bet if you call Norco they'll sell you one. My guess is they'll sell you the 80mm for the same price as the 120mm. Maybe even tell a little fib that you own one of their cases and lost the 80mm plate and want another. :)

I really do hope you get your hands on one because I'd love to see a how-to guide on how you installed it, with pictures etc. and how well it went.

 

[jgreco]

You know, you can get one perfectly built to your exact specifications over at emachineshop, rather than trying to hacksaw up something that was designed for a different case.

 

[KMR]

Just an update. I've been busy with work and the parts took a little while to arrive (I was also waiting on an M1015 and break out cable). I received the Norco fan wall and it almost fit, which is what I was expecting. It took about a couple of hours with a pair of vice grips and a drill to get the unit mounted in the case with all the testing that goes along with it. I also mounted the 4 "new" drives, flashed the M1015 with IT firmware, and wired everything up. At the moment I am just using 3 cheap coolermaster 120mm fans I had in the case (plus extras). Everything seems to be working well. I am performing a scrub at the moment and watching the drive temps closely. So far they are all running around 39 - 41 degrees Celsius. This is a little high for my taste but the ambient temperature here is about 34 degrees Celsius so I think I am doing alright. Average temperature of drives during a scrub before all the mods was about 32 -34 degrees but that wasn't in this sort of ambient temperature either. The next test will be to set up the second pool and start scrubs on both at the same time to see what that does to my temps.

 

[KMR]

As a side note, these cases aren't meant to do what I have been doing with them and 10 drives is the absolute maximum I could cram in it. This was a frustrating build because the IStarUSA case is not very long so there isn't much room to work with here. This will work for now and as long as I can keep drive temperatures in check (I may need to upgrade the fans) I will be happy. While this is a cheaper option that some of the others I believe that the next time I need to upgrade my storage case I will be getting a BackBlaze storage pod so I will always have room to grow. It will be a lot more expensive in the short term but I think the extra expansion room will be worth it.

 

[cyberjock]

Those backblaze cases, while super cool, aren't all they're cracked up to be. Someone in the forums built one for a FreeNAS server and at one point he was tearing the thing down to figure out why the system was so horribly unreliable. The answer was expected to be that port multipliers just suck, but I don't think he ever came back to say what exactly was wrong(assuming he found the problem).

 

[KMR]

Good to know about the BackBlaze units. Out of curiosity where should I draw the line with hard drive temps here? Ambient temperature being 34 (local weather station) I know I can't expect miracles, but I want to make sure I don't cook drives doing this. I'm thinking 45 degrees is where I shut the system off and re think my plan.

 

[cyberjock]

According to Google's Failure Trends in a Large Disk Drive Population document, for longevity you should keep them below 40C.

That document is a fun read if you are into statistical data about hard drives, failure rates, etc.

 

[KMR]

Perhaps I will order those fans.

 

[cyberjock]

LOL. What's the temp of your hard drives normally?

 

[KMR]

Before the mods they ran 30 - 34 degrees I would say, but that wasn't in this sort of heat.