Category Archives: Short Tips

Short Tip: Install shellcheck on an outdated CentOS

I’ve to install shellcheck on a CentOS 7 box, this is the latest CentOS version. The tool is a great linter for bash scripts, which I want to integrate into our CI pipeline. shellcheck isn’t packaged so I will build … Continue reading

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Short Tip: Installing msgpack on outdated boxes (ruby1.9.1)

I’m using msgpack to serialize the data between my puppet agents and the masters. Recently I had to puppetize an old Debian Wheezy box. I’ve to install msgpack in advance: # gem install msgpack Building native extensions. This could take … Continue reading

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Linux Short Tip: systemd-networkd and DNS servers

You maybe have noticed that you can configure DNS servers in your systemd-networkd settings, but these addresses don’t appear in /etc/resolv.conf. You need to enable/start systemd-resolved, this daemon checks global DNS settings in /etc/systemd/resolved.conf, DNS settings for each link from … Continue reading

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Short Tip: Replacing a failed drive in mdadm softwareraid

Sometimes you check your fileserver and your raid looks like this: # cat /proc/mdstat Personalities : [raid1] [raid6] [raid5] [raid4] md125 : active (auto-read-only) raid6 sdl[1] sdh[7] sdf[5] sdk[2] sdg[6] sdm[8] sdi[0] sdn[10] sde[4] 23441080320 blocks super 1.2 level 6, … Continue reading

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Linux Short Tip: Correct IPv6 with ferm firewalling

I mentioned ferm in my last post about gluster (an iptables/ip6tables abstraction layer in perl with a nice firewall config). The default rule-set looks like this: Most people attend to C&P that blog and wrap it in domain ip6 {} … Continue reading

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Short Tip: Setup glusterfs share on Arch Linux

I made a detailed tutorial for a Arch Linux installation a few days back. This is a quick follow up post to create a Distributed-Replicated gluster share. The goal is to create a mirror for several linux distributions. A mirror … Continue reading

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Short Tip: Fiddling around with login shells

I’m currently playing around with LARS, this script collection creates a arch ISO with some post-install magic, for example setting a login shell for root. The used code is: I could boot up the image and ssh into it with … Continue reading

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Short Tip: git magic (copy changed files from branch A to B)

Let us consider the following case: I’ve got a huge project which you want to refactor. You checkout master, create a branch called cleanup and commit every change. Most of the refactoring is only style guide related so no change … Continue reading

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Short Tip: tuning Zabbix Database Part 2

[part 1] Besides disabling autovacuum you can also try to increase the performance if you have got enough free resources. There are three important options for this: autovacuum_vacuum_cost_delay I lowered the sleep between two autovacuums to 0.2ms autovacuum_vacuum_cost_limit/vacuum_cost_limit (setting autovacuum_vacuum_cost_limit … Continue reading

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Short Tip: tuning Zabbix Database

I am currently running a zabbix setup which is a bit bigger than the average ones, right now it receives ~2100 new values per second, generated by 169052 items. The data is stored in a postgresql database, and I am … Continue reading

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