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Displaying posts with tag: System Administration (reset)
MySQL + SELinux: Can't change dir (Errcode: 13)

If you're using a non-standard MySQL data directory on your Red Hat Enterprise Linux (RHEL) server, you may have seen an error like /usr/libexec/mysqld: Can't change dir to '/mysql_data/' (Errcode: 13). The key to fixing this problem is to ensure the new MySQL data directory has the proper SELinux security context. In my case: # […]

MySQL: Query caused different errors on master and slave

We ran across the following error on a MySQL slave server recent: mysql> SHOW SLAVE STATUS \G <snip> Last_Error: Query caused different errors on master and slave. Error on master: 'Deadlock found when trying to get lock; try restarting transaction' (1213), Error on slave: 'no error' (0). Default database: '<database_name>'. Query: '<query>' <snip> In this […]

mysql-snmp 1.0 – SNMP monitoring for MySQL

I’m really proud to announce the release of the version 1.0 of mysql-snmp.

What is mysql-snmp?

mysql-snmp is a mix between the excellent MySQL Cacti Templates and a Net-SNMP agent. The idea is that combining the power of the MySQL Cacti Templates and any SNMP based monitoring would unleash a powerful mysql monitoring system. Of course this project favorite monitoring system is OpenNMS.

mysql-snmp is shipped with the necessary OpenNMS configuration files, but any other SNMP monitoring software can …

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MySQL InnoDB and table renaming don’t play well…

At Days of Wonder we are huge fans of MySQL (and since about a year of the various Open Query, Percona, Google or other community patches), up to the point we’re using MySQL for about everything in production.

But since we moved to 5.0, back 3 years ago our production databases which hold our website and online game systems has a unique issue: the mysqld process uses more and more RAM, up to the point where the kernel OOM decide to kill the process.

You’d certainly think we are complete morons because we didn’t do anything in the last 3 years to fix the issue

Unfortunately, I never couldn’t …

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Book: Pro Linux System Administration

Peter Lieverdink (also known as cafuego on IRC/identi.ca, engineer on OurDelta builds and for Open Query) has co-authored a book that’s available since Monday. The title is Pro Linux System Administration published by Apress.

These days some people don’t want to bother with system administration, and either hire or outsource. Others want to find out more and do things themselves (home and small office use), and that’s the intended audience for this book.

Introducing mysql-snmp!

Thanks to Days of Wonder the company I work for, I’m proud to release in Free Software (GPL):

mysql-snmp – monitor a MySQL server with SNMP History

At Days of Wonder, we’re using MySQL for almost everything since the beginning of the company. We were initially monitoring all our infrastructure with mon and Cricket, including our MySQL servers. Nine months ago I migrated the monitoring infrastructure to OpenNMS, and at the same we lost the Cricket MySQL monitoring (which was done with direct SQL SHOW STATUS LIKE commands).

I had to find another way, and since OpenNMS excels at SNMP, it was natural to monitor MySQL through SNMP. My browsing …

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OMG!! storedconfigs killed my database!

When I wrote my previous post titled all about storedconfigs, I was pretty confident I explained everything I could about storedconfigs… I was wrong of course

A couple of days ago, I was helping some USG admins who were facing an interesting issue. Interesting for me, but I don’t think they’d share my views on this, as their servers were melting down under the database load.

But first let me explain the issue.

The issue

The thing is that when a client checks in to get its configuration, the puppetmaster compiles its configuration to a digestible format and returns it. This operation is the process of transforming the AST built by parsing the …

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All about Puppet storeconfigs

Since a long time people (including me) complained that storeconfigs was a real resource hog. Unfortunately for us, this option is so cool and useful.

What’s storeconfigs

Storeconfigs is a puppetmasterd option that stores the nodes actual configuration to a database. It does this by comparing the result of the last compilation against what is actually in the database, resource per resource, then parameter per parameter, and so on.

The actual implementation is based on Rails’ Active Record, which is a great way to abstract the gory details of the database, and prototype code easily …

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Testing environment: Installing CentOS 5.2 on VirtualBox

In the previous post of this series we installed and set up VirtualBox. We prepared it for a default install of CentOS 5.2. This time, we cover the installation of the OS itself. Changes since the last article are an upgrade from v2.0 to v2.1, and the fact that I’m running VirtualBox on my Asus [...]

OpenNMS JDBC Stored Procedure Poller with MySQL

Since a few months we are monitoring our infrastructure at Days of Wonder with OpenNMS. Until this afternoon we were running the beta/final candidate version 1.5.93.

We are monitoring a few things with the JDBC Stored Procedure Poller, which is really great to monitor complex business operations without writing remote or GP scripts.

Unfortunately the migration to OpenNMS 1.6.1 led me to discover that the JDBC Stored Procedure poller was not working anymore, crashing with a NullPointerException in the MySQL JDBC Driver while trying to fetch the output parameter.

In fact it turned out I was plain wrong. I was using a MySQL PROCEDURE:

DELIMITER //
CREATE PROCEDURE `check_for_something`()
READS SQL DATA
BEGIN
SELECT …
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