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Ondrej's blog about various things


Welcome on my blog that is randomly maintained and contains mostly documentation for various projects I work on or contribute to. Below is new condensed list of posts in chronological order. In case that you want to get in touch with me, then check out the About page for contact information. This site does NOT use cookies nor Javascript and is optimized for viewing from mobile phone.

Pacemaker 2.0 with Corosync 3.0 on Gentoo - Installation

As longtime Gentoo user I like to try out some of things I have worked with on different distros on Gentoo. This time the High Availability clustering with pacemaker came to my mind. I have worked mainly with Pacemaker 1.1.x stack on RHEL/CentOS 6/7. Looking at official repos of Gentoo these seems to be present but there is nothing for Pacemaker 2.0 which requires now Corosync 3.0 and can be tested in Fedora 28 or newer. So lets have a look how to get this to Gentoo.

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Why and how to build your personal website with Jekyll

As some projects come and go I got to situation where I needed to replace the old unmaintained Bloxsom script for generating this website with something comparably simple but still maintained. The system should be reasonable easy to install on some of the currently supported Linux distribution and allow me to use my layout and theme that I have used on site before.Doing a little search and try exercise I have ended with project Jekyll that had fit the needed requirements and seemed to be reasonably installable and customizable.

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(refreshed) Configuring High-Availability clusters in RHEL/Centos with HA-LVM shared storage using Ansible

Refreshing the ansible roles around clusters made me to revisit the nearly 1,5 year old playbook for setting up cluster with HA-LVM. What has changed since then? Playbook is longer :) But does more things in proper way than previous versions did and mostly can run in "dry-run" (--check) mode. Also this time the rgmanager cluster is omitted based on adoption of pacemaker instead of it.

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Automated fast-vm deploy with Ansible

Admittively fast-vm initial installation and configuration is not the easiest one and has several places where choices can be made. However for some people this might not be interesting or some would like to just get the thing installed with some kind of "recommended configuration ready for use". So to achieve this I have created 2 Ansible roles which if combined gets all the needed setup and ready for use. In case you don't care about any settings then you will receive applying these roles:

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New smaller images for fast-vm and commands for generating them

With upcoming version 1.2 of fast-vm you will be able to use custom sized images and therefore I have decided to make some rebuild of older ones. New images are smaller than previous ones (6GB vs 10GB) and are generated using scripts rather than by hand. This provides more consistent results and hopefully eliminate human errors where possible. Performance wise images imports on my machine 30-40% faster compared to 10GB version and are up to 30% smaller than previous versions when compressed. Scripts used to create these images are available in same repository as XML and hack files for other public fast-vm images in 'ks' subfolder. Read further on how to use them.

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pcs-modules-2: ansible modules for configuring pacemaker clusters using 'pcs' utility

Since the initial version of roles for ansible to configure pacemaker cluster there was need to have modules that will interact with pacemaker in idempotent way. Initial version of 'pcs-modules' was trying to achieve this via importing functions used by 'pcs' utility from python. Unfortunatelly this was a fragile approach as there is not a stable API for interacting with pcs. Still pcs is a good idea to use as it handles most of the sanity checking before the actual cluster altering commands are used so I wanted to stick with it. New 'pcs-modules-2' are a complete rewrite into calls to 'pcs' script instead of importing parts of it. This works much better and still allows the idempotency to be achieved.

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DevConf 2017 - Creating High-Availability cluster with Ansible

Thanks to people that attented the workshop presented on the DevConf 2017 on Sunday from 11:00 in A112. Below you will find the links for materials that were used during workshop including also README file describing needed changes for some of issues that we have hit.

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fast-vm 1.0 and UEFI boot support with OVMF

One of the noticable features of the fast-vm 1.0 is support for UEFI booting. From technical point of view only change on fast-vm side needed was automatic deletion of nvram file. To get some UEFI image working we will first need to provide UEFI firmware to libvirt. Libivrt needs actually 2 files for UEFI: UEFI firmware itself and UEFI variables template file. On first VM start libvirt will make a writable copy of UEFI variable template file and provide it to VM as EUFI variables store. On VM deletion fast-vm instructs libvirt to delete this UEFI variables store file. Below is example on how to add the OVMF firmware to libvirt that can be used also with fast-vm.

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Configuring iSCSI target with targetcli in RHEL/CentOS using ansible

WIth ultimate goal of setting up something more complex in clusters I have came across the qeustion of shared storage. The immediate answer was to use some iSCSI as a simple solution and as I wanted to stay at least a bit up to date with CentOS/RHEL approach this means targetcli. I have found several roles for this but as expected they were using direct shell commands with a sometimes questionable detection of current status. So the result was a quick look into doing this a more proper way. In the end the creation contains one ansible role taht is capable of setting up targecli-based iSCSI target(server) on CentOS/RHEL 7.2. Check link below for role:

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Configuring basic High-Availability clusters in RHEL/CentOS using ansible

For those being lazy and not wanting to setup the rgmanager or pacemaker cluster in RHEL/CentOS I have a good news. You don't have to anymore. I pursuit doing same stuff over and over again I have created 2 ansible roles that should help in setting up the High_Availability clusters in RHEL/CentOS environment with minimum of effort. Check links below for roles:

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Blog moved to https://ssl.famera.cz/blog/

After long time I have resurected the blog and moved it to my home server on different address. Enjoy that blog is now accesible through https. Moreover there are small style changes which makes the page to be "responsive (=mobile friendly) thanks to my friend Dman.

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RouterStation Pro AP

I'm in search of perfect wireless AP (Access Point) for 802.1n standard which would be based on highly configurable system like OpenWRT or similar.
Main requirements are:

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Large disk array crash course

This article is meant to be a crash course guide to problems that may arise when building good, fast, cheap and large JBOD storage.

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HP switch and IPv6

Recently i have been configuring new HP switch (2910-al series) and I decided to try IPv6 support. My expectations were like It's the same as IPv4 except addresses are different (=longer). For comparison, IPv4 configuration looks like this:

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NetworkManager & Fedora 15

As part of preparation for upcoming semester I decided to try configuring NetworkManager on Fedora 15 as primary source of network configuration. There are basically two ways how to accomplish network configuration on Fedora using NetworkManager.

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