repmgr quick start
Dear future self, this is a little copy-and-paste tutorial on how to get postgres replication running using repmgr.
Ceph CRUSH map editing script
If you're working with Ceph, you'll find yourself updating the CRUSH map sooner or later. For that, you regularly need to get the current map, decompile it, edit it, comile it and upload it again. Here's a little script that makes this easier.
Prometheus quick start
Here's a little quick start procedure I like to use to get the Prometheus monitoring system up and running, featuring Prometheus itself, the node and SNMP exporters, separate directories for configured and discovered targets and a couple of basic alerts.
So far, I used this on Ubuntu 14.04 and Debian Jessie.
Samba "chmod 777" config without security=share
I regularly find myself in need of a samba config that shares a directory and "just friggin works". In those situations, I don't need authentication, user permissions or anything - I really just need the thing to work and copy files.
I even had a config that did this, but it seemed to depend on "security = share", which has been removed in a recent version of Samba 4. Luckily, I had a couple other options in that config that caused it to work even though recent versions of samba use "security = user".
FreeRadius PEAPv0+MSCHAPv2 howto
I've recently been asked to set up a wifi network using user authentication against Active Directory via RADIUS, specifically using the PEAPv0/EAP-MSCHAPv2 protocol combination. This kinda stuff has potential for frustration, but I finally got it to work. Here's how.
PROBLEM: gc Concurrent Mark Sweep in fire fighting mode
Ever since I deployed Zabbix in our local network, I've been sporadically receiving notifications about the Java garbage collector being in fire fighting mode. Unfortunately, Google isn't all too helpful about what that means. Here's how I understand it currently.
Disk alignment and caching
So now that we've conducted measurements and run benchmarks, what do we do with the results? How does the system need to be built to deliver good performance? What options do we have?
How to run relevant benchmarks
The energy needed to refute benchmarks is multiple orders of magnitude bigger than to run them.
Running a benchmark is easy.
Finding out whether you can learn anything from it is hard.
Here's what to do, and much more importantly: What not to do.
Measuring storage performance
The first step in performance tuning is measuring. This sounds pretty easy at first, but is actually a really hard thing to do correctly. This is partly because monitoring tools show irrelevant metrics and hide the important ones, and partly because we're accustomed to looking the wrong way.
User-friendly GIT CLI
How to get a user-friendly GIT CLI: