It's All About the Power

The supply of electricity in our apartment is not ideal. While I made sure to have everything re-wired properly during the renovation we did before moving in, the wiring in the rest of the building is not that great. It probably is mostly still the same as when the house was built in 1967, so it really struggles to keep up with modern consumption. At least once in a couple of months, the power goes out for several seconds and I have to re-set the clock on the microwave oven. Every once in a while the lights would dim for a split second, attesting a voltage drop. Things are worse in winter when neighbours dig the electric heaters out of their closets.

It isn’t that big of a deal usually. My desktop PC doesn’t even notice most of these disturbances, thanks to its awesome power supply unit¹. Laptops don’t care. The TV sets rebooting is a minor nuisance. However, the Raspberry Pi server with its USB-attached RAID is another story. It takes time to boot up with all the checking, I’m always worried about the filesystems, and rebooting in the middle of a rsnapshot run is never an awesome idea. I used to have a UPS unit there, but it went belly-up a couple of years ago. I didn’t bother to replace it until a fortnight ago when I finally had enough with the voltage drops and ordered the cheapest model worth looking at that the online market had in stock. It arrived several days later, I plugged it in, and the mystery was solved.

99 times out of a hundred your problem is the power supply.

– common wisdom of the Raspberry Pi community

My Raspberry Pi was a gift from a friend², and the package included the original power supply unit, the one with a button. I always assumed I was totally covered power-wise; after all, I use the power supply, what can possibly go wrong?! Well, the uptime is 10 days and counting, even with the IPFS daemon running³. There hasn’t been a single outage that would make the UPS go on battery yet, but it does serve to level out the mains voltage drops. Which seems to be exactly what the Pi’s power brick was desperately lacking, to the point of the Pi rebooting itself when the load became too intense.

Rather obvious in hindsight.