25th of November

Not a great deal to report since the start of the Pi Rack build. I haven't ordered the additional Pi's to finish it off so it has stalled. Maybe Santa will bring some in time for Christmas. I do however have the 12 Pi3 model B+ in my Pi^4 case running 24/7 so there are 48 tasks in progress at any one time.

The Raspberry Pi foundation released the A+ model as the final version of the Pi3 so now we wait for the Pi4 to be released. We will have to wait and see what comes next. I expect it will follow the same form factor as the Pi2 and Pi3 and I am sure they'll use a smaller process to they can cram more into the SoC. My wishlist:

1. More cores.
2. Faster cores.
3. More memory (2GB at least, 4GB would be nice).
4. Faster memory (DDR4 maybe).
5. Faster networking (true gigabit would be nice).

I would note that the Linux kernel has been seeing some changes to support an ARM v8.5 (yet to be announced) so maybe that is what it will get. Hopefully they'll get the operating system into 64 bit mode. The ARM v8 already supports it but Rasbpian is currently a 32 bit operating system.

BitScope Blade Rack 20 build (part 2)

Here is a picture of them without the flash so you can see the LEDs on the Pis. There is also a red LED at the end of each Blade Duo indicating they have power, although you can't see them in this photo as the red power plate covers them.

These 8 Pi3 model B+ have been running for a week or so now and haven't given any invalid results so far. I put that down to the better power supply than my USB chargers.

This is the power supply. These are normally used to run 12v LED lights in your ceiling (sometime called down lights) but this one is a 24 volt 10 amp output to make sure there is enough juice for all 20 Pis.

And this is the way they stand when one puts the rack parts around it. The top and bottom bits of the rack screw into the metal standoffs that you can see.

There is another pair of power plates and their 5 Duo's which stand next to this. However before I can do that I need to order more Pis.

BitScope Blade Rack 20 build (part 1)

You get 10 of these BitScope Blade Duo's. They hold 2 Pi's per Duo. You can see the power regulator circuit on the right.

You get a pile of 10mm nylon standoffs and M2.5 screws

Here is one of my Pi3 with its 14x14x14mm copper heatsink.

And it doesn't fit! There isn't room for the heatsink.

When I asked about this they said they don't normally use a heatsinks with them. They were kind enough to give me a number of aluminium heatsinks that are 5mm tall which would fit, however I haven't used them. Instead I bought more Pi3's rather than trying to remove the heatsink from the ones I already have.

Here is the first Duo in between the two power plates. One power plate is red and the other black so you don't mix up the polarity. The Duo is secured onto the metal brackets using M3 screws that are supplied. Due to the tight fit you add the Rpi after you've got the screws in.

And here is another shot of it before adding in the Pis.

Two Pis installed. The Pi plugs in via the GPIO pins and then you add the M2.5 screws to hold them in place.

Here I have done 8 of them, at which point I ran out of Pis. I need to add another Duo between the two power plates and this one is done.

Powering Pi

I also did some work on the NFS server last week. Its a Pi3 model B+ with a PiDrive and the Y split power cable. It was plugged into one of my 5 port USB chargers which can provide up to 2 amps.

I plugged in a Seagate Expansion 3TB drive which has its own 12 volt power adapter. While copying the files across the power LED on the Pi kept going off for a couple of seconds before coming back on. Thinking the USB charger might not be up to the job I plugged it into one of the official 2 amp power adapters. Same problem. Even after I had unplugged the PiDrive so only the Seagate was plugged in the power LED still kept going on and off when accessing the disk.

The 2 amp official Pi power supply obviously is not enough. Its no surprise they have a 2.5 amp power supply these days. I decided to get a couple of the 2.5 amp power adapters to go with the two PiDrives and have gone back to using just the PiDrive.

I will have to try it again some time when I need more disk space. What I'd really like to try is having 3 or 4 drives plugged into a Pi with them running ZFS on Linux. Dream on. ZFS requires a 64 bit operating system and Raspbian is 32 bit at the moment. And then there is the lack of memory...