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Displaying posts with tag: mysqld (reset)

mysqld_multi: How to run multiple instances of MySQL
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The need to have multiple instances of MySQL (the well-known mysqld process) running in the same server concurrently in a transparent way, instead of having them executed in separate containers/virtual machines, is not very common. Yet from time to time the Percona Support team receives a request from a customer to assist in the configuration of such an environment. MySQL provides a tool to facilitate the execution of multiple instances called …

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mysqld_multi: How to run multiple instances of MySQL
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The need to have multiple instances of MySQL (the well-known mysqld process) running in the same server concurrently in a transparent way, instead of having them executed in separate containers/virtual machines, is not very common. Yet from time to time the Percona Support team receives a request from a customer to assist in the configuration of such an environment. MySQL provides a tool to facilitate the execution of multiple instances called mysqld_multi:

…  [Read more...]
Systemtap solves phantom MySQLd SIGTERM / SIGKILL issue
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The Percona Managed Services team recently faced a somewhat peculiar client issue. We’d receive pages about their MySQL service being unreachable. However, studying the logs showed nothing out of the ordinary…. for the most part it appeared to be a normal shutdown and there was nothing in anyone’s command history nor a cron task to speak of that was suspicious.

This is one of those obscure and peculiar (read: unique) issues that triggered an old memory; I’d seen this behavior before and I had just the tool to catch the culprit in the act.

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Contain oom-killer
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Amazon micro instances is the great start option for small websites. Learn how to contain oom-killer that may make wrong decision.

oom-killer as MySQL vs Apache arbiter

When it comes to competition for memory oom-killer steps in. I run Apache and MySQL on the same box. This you should probably never do, but I thought that on my tiny setup they will get along. That’s not true. It started when first users came in. The system ran quickly out of memory:

Feb  5 03:48:26 app-01 kernel: [3313052.688189] httpd invoked oom-killer: gfp_mask=0x201da, order=0, oom_adj=0, …
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Auditing MySQL With Mcafee Audit Plugin
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Audit MySQL isn’t an easy task by default, you can use some technics like tcpdump, write a parser for general log, use MySQL proxy, or you can use some of audit plugins available out there(Mcafee MySQL Audit Plugin or MySQL Enterprise Audit Log Plugin for example).

On this post I’ll cover the Mcafee MySQL Audit Plugin (https://github.com/mcafee/mysql-audit), on a follow-up post I’ll talk about MySQL Enterprise Audit Log Plugin.

The installation is easy and require just a few steps, I’m using MySQL 5.5 32 bits, so …

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Understanding SHOW VARIABLES: DISABLED and NO values
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When you use SHOW VARIABLES LIKE “have_%” to see whether a particular feature is enabled, you will note the value of NO for some, and DISABLED for others. These values are not intrinsically clear for the casual onlooker, and often cause confusion. Typically, this happens with SSL and InnoDB. So, here is a quick clarification!

  • NO means that the feature was not enabled (or was actively disabled) in the build. This means the code and any required libraries are not present in the binary.
  • DISABLED means that the feature is built in and capable of …
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The Problems of Managing MySQL’s Configuration
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I want to keep a record of the configuration of the MySQL servers I manage. The configuration of some servers differs from others and over time the configuration may vary, partly as a result of upgrades in the mysql version or the use of the particular mysql instance, so tracking this is important.

Configuration items in MySQL can be thought of in 2 separate parts: the static configuration files which determine the behaviour of the server when it starts up (my.cnf) and the running configuration of the server in question. The latter information is usually obtained by running SHOW GLOBAL VARIABLES and SHOW SLAVE STATUS if the server is a …

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Syntax for Creating a Windows Service for MySQL (when there are 2 paths which both contain spaces)
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Numerous times now, I’ve seen people have troubles creating MySQL services on Windows manually (using ‘sc’), whether it be for mysqld itself, MySQL Proxy, or the MySQL Enterprise Monitor and/or Agent.

The proper syntax for ‘sc’ can get tricky when you have spaces in pathnames, which is very common in Windows, and the need for –defaults-file (which means two paths each potentially containing spaces).

So, if you have spaces in both your binpath and your path to –defaults-file, then the following syntax will work for you (all on a single line):

sc create MySQLEnterpriseMonitorAgent
binpath= ""C:Program FilesMySQLEnterpriseAgentbinmysql-monitor-agent.exe" …
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How to crash mysqld intentionally
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While some may think I’m daft, I have a legitimate reason for wanting to crash mysqld. However first we need to find a way to crash it.

Great thanks to Alan K, Mark L, Harrison and Hartmut on #mysql-dev for several suggestions and a config option I was unaware of. My investigation even lead to a documentation bug logged as #51739.

My first thought was to find a known bug and if necessary install the correct version to test that. A good one was suggested, Bug #48508 which fails on several versions …

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Tool of the day: inotify
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I was actually exploring inotify-tools for something else, but they can also be handy for seeing what goes on below a mysqld process. inotify hooks into the filesystem handlers, and sees which files are accessed. You can then set triggers, or just display a tally over a certain period.

It has been a standard Linux kernel module since 2.6.13 (2005, wow that’s a long time ago already) and can be used through calls or the inotify-tools (commandline). So with the instrumentation already in the kernel, apt-get install inotify-tools is all you need to get started.

…  [Read more...]
Showing entries 1 to 10 of 11 1 Older Entries

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