Supermicro SC946 - anyone?

[tc60045]

I'll start my own thread here with an admission: I own one. Bought it cheaply on eBay and I have not yet put it into use.

At the right price, 90 bays of SAS3 connectivity in one box with great redundancy is heaven. But, in practical use, the co-axial fans are utter hell. They scream. Remove one and the others spin up higher. 8500 rpm is the very low end at which the firmware will let them operate. They are the loudest fans on the Supermicro matrix, rated at 76db apiece, but I get 86db from five of them at 1m away.

I think we need a support group here -- at least I need a support group. And let this thread serve as a warning to others: these are not cheap boxes and they will ruin marriages UNLESS there is a way to better control the fans.

I'm currently:
- looking for insights as to where, precisely the EXP1, EXP2, EXP3 sensors live, as those get very hot very quickly unless all 5 fans are plugged in.
- about to pull apart the back of the chassis to find the above and see how I can defeat all five fans at once -- without re-wiring all five fans individually
- wondering whether anyone here has found it possible to use Supermicro's firmware tools to change settings like minimum fan speeds and step-down fan logic
- eager to track down the guy who manages this product for Supermicro...

 

[Aestr]

- eager to down the guy who manages this product for Supermicro...

I think if you confronted him about the issues running this chassis in a home environment he'd probably have a good laugh. With 90 drives to cool this is designed with only thermal considerations in mind.

Are you actually running 90 drives in there, or have a plan to in the future? If not the SC847 36/44 drive chassis might suit you better as you can control the fan speed with a motherboard or JBOD3 controller. Also there is some wiggle room to put in quieter fans without heating up your drives too much as it only has to move air through 1 or 2 drives instead of 6.

I know buying a new case might not be what you want to do, but for the sake of your sanity and marriage it might be the least expensive solution .

 

[i386]

- looking for insights as to where, precisely the EXP1, EXP2, EXP3 sensors live, as those get very hot very quickly unless all 5 fans are plugged in.

Expander 1, expander 2, expander 3 would be my gues, so at the bottom of the chassis/under the hdds.

- wondering whether anyone here has found it possible to use Supermicro's firmware tools to change settings like minimum fan speeds and step-down fan logic

There are quiete a few threads on sth about chaniging the fan treshholds/rpms. But with 90 hdds in 4u and expanders that would be too dangerous for me.

 

[Blinky 42]

I have one as well - Unfortunately not had enough time this summer to do any more serious testing than verify it worked once it was finally delivered after shipping debacles from the ebay seller. Except for testing, I wouldn't run it @ home long term anyway - in addition to the noise, the resulting power bill would be painful to justify at best

I would be careful modding it too much if you do want to have a lot of drives in there unless you can externally force a lot of air through the chassis or keep it in an environment where it is going to be cool regardless.

 

[tc60045]

Are you actually running 90 drives in there, or have a plan to in the future? If not the SC847 36/44 drive chassis might suit you better as you can control the fan speed with a motherboard or JBOD3 controller. Also there is some wiggle room to put in quieter fans without heating up your drives too much as it only has to move air through 1 or 2 drives instead of 6.

I'll be running 24 when I migrate, and probably 48 in a year, but I doubt I'll ever run 90. I thought about the 847 and you are right -- I may have to hit reverse and pick one up.

I am less worried about heat, but I'll expand on that in a moment....

Expander 1, expander 2, expander 3 would be my gues, so at the bottom of the chassis/under the hdds.

I think you are right! They get to 127 degrees celsius in mere seconds, so I may see if I can augment the heat transfer from them -- carefully

To both: I think this case is way over-ventilated. The pressure from all 5 of these fans blowing at top speed is remarkable. I clocked db at 86 and it is across a broad range of frequencies, so it doesn't drop as you'd want. SuperMicro rates them at just under 159CPM. Multiply by 5 and you have 800 CFM. Use the CFM = 1.79 Watts / Delta_T formula and you get that at full speed and with a case full of 90 drives putting out 12 Watts each (the observed maximum for my SAS drives), you get 2.43 Delta_T. So air going out is 2.43 degrees higher than going in. Probably makes sense for a data center and for a wide range of operating temperatures.

But in my furnace room, I can handle a much higher Delta T -- I'm starting at 20 - 25C, depending on the season, so with this full of drives and the fans blowing at 20%, I'll only then get a Delta T of 12C, so that exhaust is 37C at worst. Considering it won't be more than half full for a while and that Delta T is 6C -- or I can slow the fans more. Oh, and what about when the drives are largely idle?

Granted this temperature formula is always given with the caveat that fans are never as powerful as their rating, but I think I'll be OK messing with fan speeds. I'm even contemplating taking the top cover off and putting a big-but-quiet box fan (Vornado panel fan) in the rack. Call me crazy...

 

[tc60045]

I have one as well - Unfortunately not had enough time this summer to do any more serious testing than verify it worked once it was finally delivered after shipping debacles from the ebay seller. Except for testing, I wouldn't run it @ home long term anyway - in addition to the noise, the resulting power bill would be painful to justify at best

I would be careful modding it too much if you do want to have a lot of drives in there unless you can externally force a lot of air through the chassis or keep it in an environment where it is going to be cool regardless.

Welcome to the 86 decibel SC 946 club! My progress is tracking just like yours.

 

[Blinky 42]

Welcome to the 86 decibel SC 946 club! My progress is tracking just like yours.

Heh - on par with the other things I have at the colo so not to worried about it (stack of first-gen supermicro twin server, old Nexsan units etc).

If you do decide to part with it and have all the bits and bobs still let me know, I have considered picking up another for an upcoming project at work.

 

[e-rock]

Ancient thread, but I have a couple of these as well, know someone with a few more, and have figured out the fan control (sorta). Short answer is to send IPMI raw commands to fix the fan RPM:

raw 0x30 0x70 0x66 0x01 0x00 0x30

The last hex code there is the speed, 0x00 is full speed, 0x30 produces about 7900RPM. More details on r/HomeDataCenter.

Are you all still running them?

At 23C inlet temp, 7900RPM on the primary bank of fans, I've got the drives (all 90) running under 35C, but the expanders are brushing into the 80's.

I'm running them in a TrippLite SRQP42UB ~20dB sound dampening rack. I had to rig up a custom plenum on the back with an AC Infinity growtent fan to adequately exhaust them though. Overall between the fan control, rack, and the fact that they're in my garage, they've become tolerable.

Also if anyone is looking to unload any of these in the SF bay area I might be convinced to pick up one or two more....