Recently we encountered some strange issues with httpd on some of our CentOS 7 machines during my current project.

Through our pipeline we restart httpd several times which sometimes leads to this error:

Apache: [error] (28)No space left on device

After some research we found out the semaphores were all being used blocking httpd daemon to restart.

The list of semaphores can be fetched by issuing

# ipcs -st

------ Semaphore Operation/Change Times --------
semid    owner      last-op                    last-changed
753664   apache      Not set                    Mon Feb 17 20:20:47 2020
786433   apache      Not set                    Mon Feb 17 20:20:47 2020
720898 …

A few months ago we moved into a brand new office which was furnished with a dozen of samsung displays. Unfortunately the basic player included in those displays isn't capable to add a webpage/url as content. Since we've setted up a smashing instance to create dashboards for each team this was a huge bummer.

While looking for a stable solution many teams brought their own raspberry pi's, chromecasts, airtame devices to at least be able to show something on the displays in the meanwhile.

Since we already had good experiences with an intel compute stick and an intel NUC …

I got some issues with my wired connection lately that the speed wasn't negotiated correctly and it felt back to 10Mb/s as default.

Did some troubleshooting by eliminating various network devices, restarting them but the results didn't satisfy. Being completely random when and when not auto negotiated.

Before becoming insane I decided to update the bios of my machine (being a lenovo T460s).

I did this already in the past and talked about it even on one of our monthly last Friday's at work. So I was quite sure I had something written about it for future reference but …

Printing

Probably like many amongst us the time of the Christmas holidays is perfect to get some IT related stuff back on track. I used to have a print server setup which got broken over time and I didn't found the energy to invest time into fixing it. But the pressure became higher and higher. 111 From both my wife and daughter, especially during the holidays where the wife want to use it to print out tickets and the daughter want to print out color plates..

So during one of the evenings I pulled myself together and installed ArchLinux ARM …

Since a few years now I'm a happy Archlinux user. I like their philosophy which was one of the major points why I made the switch back in the days.

I'm not only using it on my laptop, but do have some devices running at home which are configured with it. From a thin client which I use as a docker node through some raspberry pies running ArchlinuxARM.

Since Arch is a rolling update distro there are several updates available throughout the day. To keep on top of them I had to log in on all those devices at least …

When refactoring a check_memory I wrote a few years ago I bumped into the feared

NRPE: Unable to read output

error message on our nagios instance.

When looking for a solution I went through most possible debug steps I could think of and which are nicely described by nagios support but didn't found any solution.

I almost grabbed to some anti depressants when I thought of the thing I always forget about.

SELINUX

When crawling through the audit log it became clear I forgot to configure the proper selinux context type for the new script.

type=PATH msg=audit(1518702310 …

many years ago I created my own webpage, it all started with pure, HTML evolved to a wordpress and finally became a pelican based setup. It got served on many different hosting providers but since a few years it's running on S3 storage and hosted through cloudfront all over the world.

It's a very fast setup, and once the site has been deployed and every little service has been configured and implemented the only thing I need to do is writing content in markdown without having to consider how to deploy or how it will look.

In this post I'll …

for one of my projects, the sms-twitter wall setup, I configured a raspberry pi with 2 wireless network interfaces to connect through a hotspot enabled on an android device. I discovered on previous events that the wireless adapter failed on me from time to time. So I went to the internet to look if I could add a second interface and bond them together.

I found a lot of documentation on how to bond an active-backup strategy with a wired and a wireless interfaces but didn't found a setup with 2 wireless interfaces. After a while I figured out how …

A long time ago I was active in the local scouting group. To earn some money to keep our group in a healthy financial position we organized a so called vedettweekend. It's an event where people can have a beer, vedett obviously spin a dance, enjoy a spaghetti and have a good chat with your friends.

I always played with the idea of creating a social media wall on one of the projectors we rented for the event. But I never found/made time for it, until today.. My youngest brother is who's interests are overlapping with mine brought up …

I decided to bootstrap my new machine with btrfs as filesystem instead of ext4 LVM volumes. By following the excellent arch-wiki btrfs page I successfully crafted a base system with sub volumes, limited on size and snapshots enabled.

Everything went fine, installed all the other stuff I needed, pulled in my data and was ready to go.

Obviously on that very moment disaster happened.. Due to an unexpected interrupt the journal went corrupt. When trying to boot I got stuck right after decrypted the disk failing to mount my btrfs root volume.

Uncool, unpleasant, .. I almost got insane..

So back …