IBM DAS with 12x1tb HDD.

Kryak

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Jan 17, 2020
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Waltham, MA
If it was work without errors - you can change resistors for quiet/power options.
Don't forget check HDD temperature.
If 'dirty resistor hack' not work... only one alternative - look for quiet blower fan.. it willbe not easy.
 
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Oddworld

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Jan 16, 2018
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I don't think a 47 ohm resistor would do anything. The fan is 12Vdc at 2.95 Amp. Assuming the "normal" operating voltage is 9Vdc at 900 mA, then I think we would need a 2 ohm resistor capable of dissipating a little over 1W. Do you agree?

I can't seem to find anything on ebay with that resistor. Where can I buy the 3Pin male and female "leads" to add my own resistor? Presumably, leads with large enough wire gauge to actually handle 2-3 Amp if needed (AWG #24 or better).





Original fan voltage: 9V

Original fan current: .9A

V=IR (Ohm's Law), so 9 = .9R => R = 9 / .9 = 10

Fan resistance: 10 Ohms

Target voltage: 7.5V

V=IR (Ohm's Law), so 7.5 = 10I => I = 7.5 / 10 = 0.75

Target current: 0.75A

Voltage drop across resistor: 9V - 7.5V = 1.5V

V=IR (Ohm's Law), so 1.5 = 0.75R => R = 1.5 / 0.75 = 2

Target resistance: 2 Ohms

Power dissipated by resistor: 1.5V * 0.75A = 1.125W
 
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Kryak

Member
Jan 17, 2020
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29
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Waltham, MA
I don't think a 47 ohm resistor would do anything. The fan is 12Vdc at 2.95 Amp. Assuming the "normal" operating voltage is 9Vdc at 900 mA, then I think we would need a 2 ohm resistor capable of dissipating a little over 1W. Do you agree?

I can't seem to find anything on ebay with that resistor. Where can I buy the 3Pin male and female "leads" to add my own resistor? Presumably, leads with large enough wire gauge to actually handle 2-3 Amp if needed (AWG #24 or better).





Original fan voltage: 9V

Original fan current: .9A

V=IR (Ohm's Law), so 9 = .9R => R = 9 / .9 = 10

Fan resistance: 10 Ohms

Target voltage: 7.5V

V=IR (Ohm's Law), so 7.5 = 10I => I = 7.5 / 10 = 0.75

Target current: 0.75A

Voltage drop across resistor: 9V - 7.5V = 1.5V

V=IR (Ohm's Law), so 1.5 = 0.75R => R = 1.5 / 0.75 = 2

Target resistance: 2 Ohms

Power dissipated by resistor: 1.5V * 0.75A = 1.125W
Yes, if you can solder - just buy 3 wire fan extension and "play" around resistors.
If you have regulated power supply, connect fans to power supply and make you choice about amperage for fans. After that use OHM law to determine correct resistor.

(Sorry for my language, I'm actually Russian and my English so bad..)
 
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Samir

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Jul 21, 2017
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I can't seem to find anything on ebay with that resistor. Where can I buy the 3Pin male and female "leads" to add my own resistor? Presumably, leads with large enough wire gauge to actually handle 2-3 Amp if needed (AWG #24 or better).
Here's a nice plug and play solution:
STW 1 Channel 3 Step Fan Speed Controller for CPU Fan

They also have several other solutions including a thermal swtich:
modDIY Adaptor 3Pin Fan Speed Reduction Cable (10cm)
Automated Thermal Switch 40 Degree Threshold with 3 Pin Connector
Fan Power Lead Reduction 25%/50% (2-Pin 3-Pin 4-Pin)
Fan Variable Speed Controller
PC Cooler Single Fan Control
 
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Kryak

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Jan 17, 2020
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Waltham, MA
Folks, it's just a noisy DAS, one resistor will be more them enough.
Don't need put overkill device.
Or put Arduino(Esp32) and control all HDD temperatures, air intake temperature, air exhaust temperature and mail client for warning messages...
 

altmind

Active Member
Sep 23, 2018
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What SAS controller do you use? With LSI Logic MegaRAID SAS 2108 [Liberator] (rev 03) I only see the enclosure itself, not the drives inside.

OLD: Host: scsi10 Channel: 00 Id: 52 Lun: 00
Vendor: IBM-ESXS Model: EXP3000 Rev: 01C1
Type: Enclosure ANSI SCSI revision: 04

Do I need a specific IBM sas controllers to see the drives in linux?
 

Kryak

Member
Jan 17, 2020
28
29
13
Waltham, MA
What SAS controller do you use? With LSI Logic MegaRAID SAS 2108 [Liberator] (rev 03) I only see the enclosure itself, not the drives inside.

OLD: Host: scsi10 Channel: 00 Id: 52 Lun: 00
Vendor: IBM-ESXS Model: EXP3000 Rev: 01C1
Type: Enclosure ANSI SCSI revision: 04

Do I need a specific IBM sas controllers to see the drives in linux?
I use Dell PERC H200E 6Gb/s SAS Dual Port HBA Host Bus Adapter PCI-E Card 12DNW for sale online
with ITmode flash.
No any problem with visibility.
Press enter and open shelf in BIOS.
 
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Oddworld

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Jan 16, 2018
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Is there any practical way to upgrade the SAS controller to upgrade these from SAS 3Gb/s to SAS 6Gb/s? Or is that even necessary for spinning rust drives?
 
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Efigalaxie

New Member
Feb 1, 2020
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The dell h200e hba works just fine with these...right out of the box. They aren’t that loud in my opinion.
 
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Oddworld

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Jan 16, 2018
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I think the eBay description was wrong - these use SAS1 expanders at 3Gb/s not 6Gb/s. See my other post here: https://forums.servethehome.com/ind...00-16e-slow-performance-using-8-drives.27454/

I'm new to DAS hardware so am not sure whether this is acceptable. For spinning rust, I can reach the SAS bus limit with 8 of the 12 drives. SSDs would reach the limit much faster.

Let me know if anyone has any recommendations.
 
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