15Bay NAS (15x2TB HDD) – SAS Expander

I was looking for a fast and easy way to expand my NAS. I wasn’t interested in building an entirely new server. I only wanted to get more disks connected and without incurring the additional cost of running another server. My current setup consists of 8x2TB HDDs in an external enclosure connected to the server via e-SATA (here) this was working fine but it didn’t allow for expanding to a much larger number of disks. SAS Expanders turn out to be a good choice in terms of technology for achieving the goal of connecting many hard disks to a server, being able to scale via daisy chaining expanders, and operating without a full motherboard/cpu/memory. The enclosure I was currently using costs about $240 for 8 bays. I will show you how to get 15bays for not much more and it allows for you to scale. What do you get for less than $1000? 15x2TB of storage with possibilities to scale into the future.


  • These particular parts I selected will operate with 2TB hard disks but will not work with any larger disk sizes (3TB, 4TB, etc). This is because most of these parts are older generation and use SAS1 technology. If you want to support larger disks then you would be looking for SAS2 parts and backplanes. But the costs of the SAS2 backplane and supporting chassis as well as the difference in cost between 2TB and 4TB hard disks makes it more cost efficient to use older 2TB hard disks.
  • I didn’t want an entire server, so this build doesn’t have a motherboard or any other components. I ended up selling the parts that came with the SuperMicro 933T. This cuts down on power usage and improves airflow through the case. It also allows me to add more disks to the inside of the case (the SAS expander supports up to 24 hard disks) if needed.
  • Why not just a tower case with lots of internal bays? I thought about using something like that because it would probably be less costly than purchasing a 15bay server. The trade off is with the 933T chassis you get redundant power supplies (dual psu with one backup) and easy access to external swappable drive bays, making the 933T a more attractive solution for me.
  • Without a motherboard you need to bridge the ATX motherboard pins to get the power supply to turn on, check out this tutorial (green + black). I will write another post about how I re-enable the power button on the front panel and control the chassis fans using an Arduino + temperature sensor!

The Parts 

  • $4 Molex Power Cable Extension 12″ – here
  • $5 PCI-E Molex Power – here
  • $10 SAS RAID Controller – here
  • $13 Small Flat Hard Disk Screws – here
  • $14 Mini SAS to 4-SATA SFF-8087 Forward Breakout Cable – here
  • $25 External Mini SAS SFF-8088 Male to Internal Mini SAS SFF-8087 Male – here
  • $39 HP Proliant 24 Bay 3Gbps SAS PCI E Expander Card – here
  • $245 15 Bay SuperMicro 933T – here
  • $510 15 2TB Hard Disks- here

Some Assembly Required

  1. Remove the motherboard with CPU and Memory.
  2. Attach the HP SAS Expander to the PCI-E Molex Power adapter.
  3. Screw the SAS Expander to the back of the case.
  4. Attach the Chassis Backplane to the SAS Expander (4×4 Forward Breakouts).
  5. Connect an empty Molex to the PCI-E Power Adapter using the Molex extension cable.
  6. Screw in the 15x2TB hard disks to the disk caddies that come with the SuperMicro 933T.
  7. Pop all of the hard disks into the chassis.
  8. Attach the SAS RAID Controller to the server that will be attached to this array of disks.
  9. Connect the SAS RAID Controller in the other server to the SAS Expander in the NAS.
  10. That’s it! Power up the NAS by connecting the green and black pins in the ATX connector.

Interested in taking this build to 24bays instead of 15bays? I chose 15bays because the costs of additional hard disks for 24bays would make this project more than $1000. If you want to do 24bays then you just need more hard disks and a chassis that will take 24bays like here. The SAS Expander already supports 24bays and the other parts would be the same!

Some Photos

All of the Hard Disks!

Hooking up the SAS Expander and Chassis Backplane.

Notice the Molex extension cable to connect to the PCI-E Power adapter.

You will also probably notice the chassis fans are currently not hooked up. You can hook these up to the ATX motherboard pins or another spare molex but in my next post I will detail the use of an arduino and temperature sensor to drive the chassis fans.

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