BUILD Switching out 1 x BPN-SAS-846EL1 for 2 x BPN-SAS2-826EL1

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Mar 27, 2015
I've been dabbling in FreeNAS since early 2014 and rather quickly realised a Supermicro 24 bay chassis would be the way to go for me. Finding a used one seemed rather easy as long as you lived in North America. Europe was a different story. New ones retails at $1400+. Used ones rarely surface.

I've had multiple wide eBay searches going for years without finding anything at a decent price from a seller willing to ship to Sweden at a decent charge. I collected parts over the years and experimented with building my own "Supermicro" chassis which non surprisingly proved to be easier said than done.

Fast forward to this summer. The ebay search notification email included one precious Supermicro SC846A-R920B. Within minutes I clicked "Buy now" not caring to much about the price nor the exact components included. Two days later a huge package was delivered. Finally.

Looking closer at the specs I realised that the BPN-SAS-846EL1 would need an upgrade. Among the parts I had collected was two BPN-SAS2-826EL1. It wasn't exactly a drop in replacement but without to much hassle I got it to fit rather nicely with very slight modifications to the original hardware.

I mounted the two backplane frames on top of each other using a strip of 1.5mm sheet aluminium as a spacer between them to make the gap between the lower 12 bays and the upper 12 bays line up. This strip is hard to see in the photos. I simply drilled 4 holes through the frames and the spacer and bolted them together using M4 bolts and lock nuts. That made for a very rigid "24 bay" frame.

Trying the frame in place I found out that it needed about 5mm elevation from the bottom of the chassis to align correctly. I cut a strip of 5x12mm aluminium and attached it to the bottom of the chassis using the mounting holes used by the original backplane frame. This elevated the new frame just enough. I tapped some holes in the strip of aluminium lining up with the mounting holes of the frame. Using M4 threaded rod, a piece of round 6x1mm aluminium tube as a spacer and a dome/cap/acorn nut I could mount the frames in place.

Being mounted only to the bottom of the chassis the frame showed to be surprisingly sturdy. The existing mounting holes in the backplanes did of course not align with the corresponding holes in the chassis so I had to add a few supports. Two small brackets at the very top was more than enough to keep the fram from moving at all when inserting or removing disks. Even though I planned to add more supports between the sides of the chassis and the new frame it was completely superfluous once the top brackets was in place.

Of course I forgot to document most of the build but I got a few pictures of the end result. If anyone is curious I can get into more detail and perhaps get some better pics as well.

I hope someone finds this at least a bit interesting :)

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Server Wrangler
Feb 15, 2014
Can you post the photos directly to the forums? Just copy/paste them into your message. Interesting little hack you've got there!
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