ads' corner

Pi-hole 6.x, no more 'Remember me for 7 days' checkbox

While upgrading my Pihole from 5.x to 6.x I ran into a nuisance: the session timeout for the web interface is really short. On the plus side: the session timeout is now configurable.

Raspberry Pi OS - First Steps

A long time ago I wrote down the first steps I usually do when installing a new Raspberry Pi. Now I'm installing a new system, with a 2025 Raspberry Pi OS. Time to update the notes.

How many Raspberry Pi can be operated in a Shipping Container

Back in December, during PGConf.EU 2023 in Prague, we had a discussion about datacenter hosting. Someone brought up Microsoft’s underwater datacenter experiment from a few years ago. And then someone else asked the obvious question: is it possible to run a datacenter in a shipping container using only Raspberry Pi computers. At first glance, this might seem impractical. But is it really? Let’s crunch the numbers and find out!

Chemnitzer Linux-Tage 2024 - Rückblick

Die Chemnitzer Linux-Tage 2024 sind vorbei, Zeit für einen Rückblick. Was habe ich gesehen, gelernt und erlebt.

Restic backup

Was asked quite a few times how I do my backups with Restic.

For more than 10 years I was using “Duplicity” for backups, but in 2019 I changed to Restic. The main reason for the change was that Duplicity still can’t handle “Big Data”, as in: larger directories. In 2009 someone opened an issue on the Duplicity bugtracker, and this problem still exists as of today. For about two years I was shifting around the problem, excluding files, trying to make the sigfile smaller. But at some point I decided that it is enough and I need to change the tool.


openHAB: faster loading of rules files

openHAB rules files are lazy loaded. When a rule is used the first time, the entire rule file is loaded and compiled, which apparently is single-threaded and takes a couple seconds. Even on a reasonable powerful Rasperry Pi 4. This happens both after restarting openHAB and after changing the rules file. It also means that whatever the rule in question is supposed to do has to wait a couple seconds when requested for the first time. Imagine you have a light switch, enter a room, press the switch, and it takes 5-10 seconds until the light comes on.

To work around this problem, I add a piece of code in all rules files which triggers an immediate action right after loading the file. This way the rules file is already pre-loaded (which again takes a couple seconds, but likely at a time when the rule is not needed right now).


Install openHABian image on Linux

My plan is to reinstall openHABian on a bigger SDcard, and on a Raspberry Pi 4. The latest release (v1.5) supports the new Pi 4, and I decided it’s time to do a fresh install, and see if all my Playbooks are still working.

As always, I’m searching my shell history for the right command how to install the image … but came up empty.


Grafana: select host for a dashboard

InfluxDB is running on a Raspberry Pi in my home network (with separate attached disk), and I installed a Grafana on top of it, to visualize crucial data.


Move InfluxDB data directory to a SDcard

For my openHAB system I installed InfluxDB (on a separate) Raspberry Pi. The Pi has a 32 GB SDcard, but that is not enough for storing all the data, and that Pi has additional work to do as well. For that reason I also attached a 1 TB disk to the Pi, and mounted it on /data. Now all I have to do is move the InfluxDB data directory to /data.


openHAB and HP printer

Recent openHAB versions come with a new HP Printer Binding, which is a big improvement over the more general IPP Binding for printers.