One node causes grief

I had problems with one of the Pi3B+ nodes in the cluster when I managed to lock it up. I thought I would power it down, put the SD card into another Pi3 and off we go. Of course that didn’t work. It decided it was going to lock the Pi user account so I was forced to wipe the SD card and reinstall which meant the 4 work units it had in progress were trashed.

The next problem was I couldn’t connect to the NFS server. It seems Raspbian has a limit of 16 connections at a time. I worked around that by logging one of the other nodes off so that I could copy the files needed.

After getting past that it decided to download the old Einstein app which doesn’t work under Raspbian Stretch so it trashed another 6 work units in quick succession. I had to update my preferences on the Einstein project in order to get it to download the correct app.

While adding/removing the SD card from this node in the Pi^4 case I also managed to break the fan power cable so the fans went off. I use USB to fan header cables which I got off eBay. The fans are plugged into this which is then plugged into the USB charger. The soldered join on the fan header pin had broken off. I had to resolder both. Just as well I still have a soldering iron. They look something this, except mine don't look as professional.

Blade Rack 20

In better news BitScope Designs have now got a Blade Rack 20 and a Blade Rack 40. I have ordered a Blade Rack 20 so I can get some of the compute nodes into a single case.

I also had to order a LED transformer, like they use for the LED down lights in your ceiling, to power it. The transformer has a 24 volt 200 watt output as recommended by the team at BitScope. The BitScope blades take 9 to 48 volts as input and provide 5 volts to the Raspberry Pi. Hopefully parts will arrive next week.