Hi,
I thought I’d post my latest project. I use a bunch of Raspberry Pi compute modules as servers and decided to build myself a custom blade server to host them. This is replacing a bunch of old Intel rack mount servers on my home network - it’s a lot less power hungry! It’s been through a few iterations and is now working really well. This is the server:
It’s a 2U rack mountable unit, in an off-the-shelf ABS case with some custom 3D printed parts. The server takes up to 10 of these blades:
It’s got gigabit Ethernet, USB-A and HDMI on the front and an NVMe SSD slot on the board, along with an SD card slot and a battery backed real time clock. There’s a little OLED on the front displaying information about the blade, including the name and IP address to make it easy to identify for maintenance. There’s also an RP2040 on it for management.
The blades plug in to a custom backplane which provides power and centralised management. There’s an LCD front panel providing basic tools for powering on and off blades and status information, and another compute module which acts as a management web server. It can be used to upload flash images to the blades via the backplane, and provides serial console access to the blades through the web interface.
I’ve been using this for a while now and was wondering if other folks out there are interested in it? It would be quite quick and easy for me to turn this into a product for sale if there was a market out there for it.
Please let me know any comments or suggestions you have, any feedback is appreciated!
Alastair
This is a pretty awesome project, and is very well done! I’d love to see more pictures!
It looks like custom PCBs for the blades and the backplane? More details on that would be very interesting.
What all are you running on this system so far, and what software do you have plans to add? Are they running independently or as a cluster?
Summoning u/geerlingguy here, I’m sure he’ll love this project!
Thanks, that’s very kind. Here’s links to some more pictures. The original ones were taken by my photographer wife and these ones were taken by me on my phone, so apologies for drop in quality!
This https://imgur.com/9eqdiGn is a view of my development test unit on the bench with the cover off. I’m using an off-the-shelf 1U PSU for power as it’s a nice easy way of getting 100W+ all delivered at the right voltage levels. It’s also the limiting factor in the number of blades that the box will take, as it takes up a decent chunk of space.
The PSU leaves just enough space at the front for the front panel board https://imgur.com/OSK9ngE. I’m using on off-the-shelf 2.4" LCD modules for the main screen and 0.91" OLED modules for the blade displays. The management CM4 is on its own little riser board as the CM is about 10mm too big to fit horizontally in the space. To keep costs down you’ll see I’m using PCI-e x1 as the card edge connectors. These are WAY cheaper than the fancy purpose built back plane connectors so do the job perfectly.
The management board, the backplane and the individual blades all have RP2040’s on them for management. https://imgur.com/YpDE1Uo is a close up of this on the management board. I could probably have done it with cheaper microcontrollers, but the RP2040 isn’t overly expensive, is easy to get hold of, and it’s nice keeping it all in the Pi ecosystem.
The backplane’s got a couple of 74HC4067 multiplexers for switching the UARTs from the blade CMs down to the management module, and four FSUSB74’s to do the same for the USB interface. There’s also a few 9535 I/O expanders, both because I ran out of GPIO’s on a single RP2040 but also to make routing easier on the 4 layer board.
I’ve mentioned on another reply some plans for the software, but mainly planning to add full status info (stats from each of the blades), along with a serial console and USB provisioning.
For my original use case, I’m actually using them all as individual servers. It replaced a bunch of VMs running on some second hand enterprise kit I had. The Pi’s are able to do basically as good a job for what I need but consume much less power (the CM datasheet puts the max typical at about 7W, so even allowing for extra overhead you’re running 10 blades at less than 100W.)
I’ll need to do a proper blog post with all this at some point soon!