A home made SAS expander. Is it a good idea or why bother?

Hello Farmers!
Those of us that use enterprise equipment try to keep our disks cool by effectively putting them in an oven and then using fans to keep them cool. After seeing some 3D-printed DIY disk enclosures, I thought I would have a go myself. I decided to base my design on the Supermicro 8 LFF expander SAS825TQ since it does not have non-proprietary connectors. Since it is a “straight-through” connector, disks should work at 6/12G. I have yet to try it out (although I don’t actually have any 12G disks to test it).
The parts are printed on a Creality Ender 3 Pro V2 (a consumer-grade 3d printer). A din rail slots into grooves on each side to hold everything together.
So I wondered if chia farmers would find this an interesting alternative or would ask why bother. So please, may I have your feedback?


This was my original scenario, which is now outdated. I think this solution is simpler than yours.
SFF8088/SFF8643 to 4 SAS/SATA cable + hard disk bracket。
A Dell R720 can put in 7 external HBA/RAID controller cards.

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Are those HDDs passively cooled or are there fans behind them that are not visible in the picture?

There are no fans (yet). A fan mounting point can be easily added on the side, or a lid with a larger fan cooling multiple units could be made. I had imagined mounting 3 or 4 units on a sliding drawer in my 19" rack. Getting the PCB aligned for the drives to do hot-swap drop-in is the challenge (mostly surmounted).

I have also shown some other ideas.

Thanks, guys, for the feedback.

I have not tried this system and avoided it because:

  1. I had assumed there would be no diagnostic LEDS making troubleshooting difficult.
  2. I was trying to reduce the spaghetti effect or wires everywhere.

I would also like to introduce you to the perfect JBOD expander should you need to add many more drives The Perfect JBOD SAS expander | for building your own DAS JBOD disk enclosure - YouTube
I have one of these. I would recommend it.

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Cool, I like it. I’m always a fan of interesting DIY setups.

I am curious though how the temperatures will be, the drives are still pretty darn close together.

So true :sweat_smile:
And the drives are so close together, that there is barely any room for air in server/jbod chassis.

Wow that is a pretty impressive looking setup! You say outdated now, how are you doing it now?

How are you powering that ? If my eyes are not deceiving me, there are 12 disk connected to a single cable?
What drive bays are those? I have so many questions :grin:

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Technically that is a back plane, not a SAS expander which is actually a card which connects to the HBA and gives you many more SAS connections.

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There are 8 drives spaces on this backpane.
To connect you would use 2 molex connectors for power two SAS connection cables that terminate in 4 sata connectors.

Seems a bit of a trade-off which backplane to use.
In this case you still end up with 8 sata ports to connect. But as you said, it doesn’t have proprietary power connectors.

Ideally you want to find a backplane that is powered by standard molex, but uses sas-8087 connectors for the data.

I know my inter-tech 4u case has a backplane like that 8x LFF with 2x sff-8087 and 2x molex.

The HP storageworks backplanes that I have , have a built-in sas-expander for 12 drives, so only 1xsff-8087 cable needed…But they use 10-pin proprietary power connectors.

I originally wanted to make a disk drawer with 1U boards but found none in the UK. In the US, I have seen some SuperMicro 1U SAS815TQ, but they take the SATA connector. I also looked for boards with 8087 connectors to connect many disks, but they tend to be more expensive because they have an onboard LSI chip. Everything seems to be a trade-off.

yeah think so to.

I got lucky with mine because it was someone who just wanted to het rid of it, so they were prectically free

How much hardware cost per hard drive?

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It’s looking pretty slick John. So… will it stay open air or will it be cooked in an enclosure/oven :wink:?

I am just thinking ahead. Summer is coming!

Thanks for sharing.

I think the biggest problem is cost per drive, that’s why jbods are popular. One other concern I have seen is disk density, where 48-60 drives servers are better and forced air works well enough to keep disks cool.

Regarding cost, backplanes don’t help, a simple expander setup achieves the same result, at the cost of cable spaghetti.

Regarding density, backplanes help a little, but in that case it seems you’re just making a JBOD for more time/money than it cost to buy a second-hand one off the shelf.

That being said, I’d love to buy custom Chia racks if the price was right :slight_smile:

Feel free to tell me if I’m missing something! Appreciate your contribution :slight_smile:

I am going with the sas/disk shelves enclosures because they are very simple, easy to manage. I have many DS4243, KTN-STL3. I acquired them at very low prices, usually around $4 per drive. At that cost, it just doesn’t worth the hassle of custom set up.

Though lately, I notice the costs may not be that low. Power usage for dish shelves/enclosures are higher. There is ~ 2 watt per disk cost due to fans and power supply. Then I have to count extra for the cost of the power for the transposer. I haven’t had a chance to measure it but it must be somewhere between 0.5 watt and 1 watt.

Given that, the real benefit of sata only custom set up is the power cost. Someone posted that their farm is 1.3PB farm consumes 385watt. That’s pretty crazy low number. Less than 6 watts per drive.

@mr-biz , what is your per drive electricity consumption?

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I use 4R rack system. It did cost me 50$ ROFL

I used to have a direct mount between Alu plate and HDDs…problem is vibrations, but extraordinary heat dissipation.

Sadly, Alu prices are +300%, so there are no more improvements.

You can buy Intel expanders for sub 100$ nowadays, and connect 16 HDDs.

I was warned about backplanes - allegedly power issues that may kill all drives connected.


I use JBOD, and get 6.2W/drive. If I add another 10 drives, I would be < 6W/drive.

I use 4R rack where HDD temps are 25-35°C

You need flow anyway. You have to account for it or buy SAS that can easily handle 40+ °C

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What is 4R? Is this related to HP?

In the picture I see a custom hard drive mounting solution with no backplanes.

PS: I edited my original post, I used the wrong terminology.