Archive
Posts from 2016
Printing tape drive serial numbers
While automating a process this week I needed a way to get the serial number off a batch of tape drives. At first I thought I could retrieve this information through /sys. But after a bunch of poking around with cat, systool and udevadm I realized I couldn't get what I want through /sys. One such failure: If I can't get the serial # through /sys I can always poke the drive directly, right…
$ read more →Creating happy little block devices with UDEV
I'm a long time admirer of Bob Ross and the amazing paintings he produced on his hit tv show the joy of painting. I'm equally a fan of udev and the power it places in administrators hands. While Bob painted amazing clouds, seascapes and mountains with a swipe of his brush I'm able to make /dev just as beautiful with a few keyboard strokes (I guess that makes my keyboard my easel). This past weekend I decided to clean up and automate the device creation process on several of my database servers…
$ read more →Using docker to build software testing environments
I've been on the docker train for quite some time. While the benefits of running production workloads in containers is well known, I find docker just as valuable for evaluating and testing new software on my laptop. I'll use this blog post to walk through how I build transient test environments for software evaluation. Docker is based around images (Fedora, CentOS, Ubuntu, etc.), and these images can be created and customized through the use of a Dockerfile…
$ read more →The subtleties between the NXDOMAIN, NOERROR and NODATA DNS response codes
This past weekend I spent some time troubleshooting a DNS timeout issue. During my debugging session I noticed some subtle differences when querying an A and AAAA record with dig: When I was interpreting the results I was expecting dig to provide a response code of NODATA when I asked the DNS server for a resource record that didn't exist. Obviously that didn't happen. This led me to ask myself what is the technical difference between NODATA, NOERROR and NXDOMAIN…
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