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Displaying posts with tag: Linux (reset)
Running Percona XtraDB Cluster nodes with Linux Network namespaces on the same host

This post is a continuance of my Docker series, and examines Running Percona XtraDB Cluster nodes with Linux Network namespaces on the same host.

In this blog I want to look into a lower-level building block: Linux Network Namespace.

The same as with cgroups, Docker uses Linux Network Namespace for resource isolation. I was looking into cgroup a year ago, and now I want to understand more about Network Namespace.

The goal is to both understand a bit more about Docker internals, and to see how we can provide network isolation for different processes within the same host. You might need to isolate process when running several MySQL or MongoDB instances on the same …

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Linux User-Group Console

This post shows you how to add the menu option and GUI to set users and groups. It’s quite a bit easier than mastering all the command-line syntax. It makes setting up the required user and group accounts for an Oracle Enterprise or MySQL database solution much easier.

You add the utility by calling the yum (Yellowdog Updater, Modified) utility like this:

yum installed -y system-config_users

You should see the following:

Loaded plugins: langpacks
adobe-linux-x86_64                                       |  951 B     00:00     
ol7_UEKR3                                                | 1.2 kB     00:00     
ol7_latest                                               | 1.4 kB     00:00     
Resolving Dependencies
--> Running transaction check
---> Package system-config-users.noarch 0:1.3.5-2.el7 will be installed
--> Processing …
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How to Setup MySQL Master-Master Replication

This article consolidates information from several sources into the format I use to setup MySQL Master/Master Replication. The beauty of Linux and open source is that there are many different ways to do this. Please take a look at my references and use them to accommodate any needs you may have.

linux memory management for servers

We’ve been learning for many years how to run Linux for databases, but over time we realized that many of our lessons learned apply to many other server workloads. Generally, server process will have to interact with network clients, access memory, do some storage operations and do some processing work – all under supervision of the kernel.

Unfortunately, from what I learned, there’re various problems in pretty much every area of server operation. By keeping the operational knowledge in narrow camps we did not help others. Finding out about these problems requires quite intimate understanding of how things work and slightly more than beginner kernel knowledge.

Many different choices could be made by doing empiric tests, sometimes with outcomes that guide or misguide direction for many years. In our work we try to understand the reasons behind differences that we observe in random poking at a problem.

In order …

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Docker for Mac beta and MySQL - First impressions

Using Docker for development is a great way of ensuring that what you develop will be the same that you deploy in production. This is true for almost everything. If you develop on Linux, the above statement holds. If you develop on a different operating system (OSX or Windows) there are several restrictions.

I showed one of those issues in a recent article (MySQL and Docker on a Mac: networking oddity.) When you want to export a port from a service running in the container, the exported port is not available in your mac, but in the virtual machine that runs Docker services. This happens with any application that listens to a port.

The second limitation I found affects only MySQL, and it is related to using volumes. The proper way of achieving data persistence with …

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Ubuntu 16.04 first stable distro with MySQL 5.7

Ubuntu 16.04 artwork by Canonical Ltd (CC-BY-SA).

Congratulations to Ubuntu on releasing 16.04 LTS with MySQL 5.7! As far as I know, it’s the first stable release of a Linux distro that contains MySQL 5.7. Fedora and openSUSE also have MySQL 5.7, but not yet in a stable release.…

Docker MySQL Replication 101

In this blog post, we’ll discuss some of the basics regarding Docker MySQL replication. Docker has gained widespread popularity in recent years as a lightweight alternative to virtualization. It is ideal for building virtual development and testing environments. The solution is flexible and seamlessly integrates with popular CI tools.


This post walks through the setup of MySQL replication with Docker using Percona Server 5.6 images. To keep things simple we’ll configure a pair of instances and override only the most important variables for replication. You can add whatever other variables you want to override in the configuration files for each instance.

Note: the configuration described here is suitable for development or testing. We’ve also used the …

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MySQL OOM'ed, But Pelican Lives

I use Pingdom's free service to monitor Apparently, late Friday night, oom-killer decided that the server needed more memory and took out the MySQL server. To make matters worse, I missed the alarm from Pingdom, and was down for pretty much all of Saturday. The fact that oom-killer was invoked is annoying, but more on that later.

The beauty of using Pelican rather than Wordpress (or any other database-driven content engine) is one less point of failure for the site. Obviously, I don't have all of converted to Pelican yet (and perhaps never will), but at least parts of the site were up and working despite MySQL being down. If nothing else, this incident is enough to convince me that moving to Pelican was a good idea.


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Deprecating the mysql_config –libs_r option

As Norvald wrote in his recent post:

A long time ago, libmysqlclient came in two versions: one that was thread safe and one that wasn’t. But that was a long time ago. Since MySQL 5.5, the thread safe libmysqlclient_r library has just been a symlink to the libmysqlclient library, which has been thread safe at least since then.

Fedora LAMP Steps

I posted earlier in the year how to configure a Fedora instance to test PHP code on a local VM. However, I’ve got a few questions on how to find those posts. Here’s a consolidation with links on those steps:

  1. Go to this blog post and install the httpd and php libraries with the yum installer.
  2. In the same blog post as step 1 (you can put the sample PHP code into the /var/www/html directory for testing), connect to the yum shell and remove the php-mysql library and then install the mysqlnd library.
  3. Go to this blog …
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