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Showing entries 1 to 7

Displaying posts with tag: mysqld (reset)

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 I’ll download the files for

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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 working in the binary, but is disabled due to relevant my.cnf settings.
  • YES means the feature is available, and configured in my.cnf.

SSL tends to show up as DISABLED, until you configure

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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 slave.

I’d also like to compare the 2 sets of configuration so I can see if a local change has been made to the running server which is not reflected in its configuration file. I might want to correct this, or

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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"
--defaults-file="C:Program FilesMySQLEnterpriseAgentetcmysql-monitor-agent.ini""
DisplayName= "MySQL Enterprise Monitor Agent" start= "auto"

Note that you could easily use the

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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 that I will use to demonstrate with, however the simplest way is to issue kill -11

By default, no core file will be produced which is what I’m seeking but with the right options this is possible. First, the user running mysqld probably has a

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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.

 # inotifywatch -v -t 20 -r /var/lib/mysql/* /var/lib/mysql/zabbix/*
Establishing watches...
Setting up watch(es) on /var/lib/mysql/mysql/user.frm
OK, /var/lib/mysql/mysql/user.frm is now being watched.
[...]
Total of 212 watches.
Finished
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mysql_install_db, mysqld --bootstrap, binary log, cPanel
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Warning... what follows is a murky mess.
It's filed as MySQL bug#43398 (verified!) but it's triggered by cPanel doing evil.

Scenario....
Start a mysql server, as normal
Then run mysql_install_db (as root, like you would when you first install MySQL)
See a new binlog file get created, with ownership/group root!
Of course you generally wouldn't run mysql_install_db while a server is running, but there's nothing to prevent you (or something else) from doing so!
--bootstrap just shouldn't initialise binlog, then there wouldn't be a issue.

cPanel runs mysql_install_db in its automatic upgrade scripts (dangerous already, automatically upgrading MySQL Server on a system!), it's run every night on cPanel systems even if no upgrade is done, and it behaves exactly as described above. It then chowns the binlog







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Showing entries 1 to 7

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