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 …

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.

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 …

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 …

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.…

A few days ago, I was struggling to install python on a Linux machine, in which I had no root permission. That machine was shared with many other users and there was only an old python version already installed on the machine. After a bit of search and trial, I was able to install a newer version of python on this machine to my local directory.

My goal was to run a program developed under python 2.7 on the Linux server which already had python 2.6 installed. As you can see, it was impossible for me to upgrade python on the system because I had no root permission. The only solution was to install the python 2.7 into my local directory and override the necessary environment variables. Even though this blog aims for python 2.7, I believe it should also be the same for python 3.0. The detailed steps are as follows:

1. Install python to local directory

Firstly, I create a folder in my home directory, download the …

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 …

We have been using SSH all the time but not all people really understand the files we put inside the ~/.ssh folder on our computer. It was a myth to me when I was first using SSH, but things are pretty clear to me now and I want to share this with all of you, just in case you don't know.

known_hosts

This file is responsible for verifying the host we have connected to. If it was the first time you connect to a host, you would probably see the following message:

The authenticity of host 'example.com (10.0.0.0)' can't be established.
RSA key fingerprint is    SHA256:VqgUG8v+gxrigR1csELYv6Un6l7HxMgPgMj9wyUr7G4.
Are you sure you want to continue connecting (yes/no)?

The moment you select yes to continue connecting, the hostname along with the public key of the server will be saved as a new line in this file. Why we need this file? Just imagine that for some reason our routing has …

In my previous post, I spoke of "Normalized" and "Non-Normalized" CPU utilization values:
--
TABLE:Foreword: Windows is not "process" based OS (like Linux) but rather "thread" based so all of the numbers relating to CPU usage are approximations. I did made a "proper" CPU per Process looping and summing up Threads counter (https://msdn.microsoft.com/en-us/library/aa394279%28v=vs.85%29.aspx) based on PID but that proved too slow given I have ~1 sec to deal with everything. CPU utilization using RAW counters with 1s delay between samples proved to produce a bit more reliable result than just reading Formatted counters but, again, too slow for my 1s ticks (collect sample, wait 1s, collect sample, do the math takes longer than 1s). Thus I use PerfFormatted counters in version 0.9RC.

Win32_PerfRawData_PerfProc_Process;  …

I use Pingdom's free service to monitor slaptijack.com. 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 slaptijack.com 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 slaptijack.com 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.

OOM'ed

…