MySQL PID changes

MySQL

MySQL server is running for 95days but the mysqld pid is changed few times.
Why mysqld changes its pid, any ideas ? How can I know that the mysqld pid has changed and what is the cause behind the change of the pid ?

Regards

Supratik

Best Answer

My guess is that the server restarts itself every now and then to avoid resource leaks (memory, connections). Many big sites ran into trouble because of that in the past (server would run out of connections and not being able to answer any requests anymore), so that probably made it into the install scripts.

If you want to find out exactly, I suggest to check the crontab of root or the user the MySQL is running under.

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Mysql – Can’t start/stop thesql service

mysqladmin shutdown

should work to shutdown the server.

I see two likely possibilities:

MySQL has a problem and is refusing to shut down for some reason.
The previous admin did something strange. Either modified the init.d script or didn't bother using the Debian packages at all to install MySQL.

What does dpkg --list mysql\* say?

What does /var/log/mysql.err say? Or the other mysql logs?

EDIT:

So mysqladmin shutdown worked?

According to that, the mysql-server package is installed (mysql-server-5.0; the mysql-server package is probably just a stub). So they may have installed over it? Running debsums mysql-server-5.0 might tell you more. dpkg --listfiles mysql-server-5.0 could help, too...

What's actually in /etc/init.d/mysql? I haven't checked that specific version of the package, but it should try to use mysqladmin shutdown ... Maybe you're lucky and they only broke that...

Mysql – Preventing brute-force attacks on MySQL

I don't know of any denyhosts-like software packages for MySQL, but I do have a couple of solutions:

Limit login to specific IP addresses. Do not use % to allow for all hosts to connect to the server.
Even more secure, set up iptables to only allow access to 3306 from authorized IP addresses.
Tunnel your traffic to the box with ssh then connect via localhost
Modify the Denyhosts or BFD scripts to analyze mysql access logs and block any brute force attempts at the firewall

Edit:

To answer your comment, try this:

iptables -A INPUT -p tcp -s 202.54.1.50 --sport 1024:65535 -d 202.54.1.20 --dport 3306 -m state --state NEW,ESTABLISHED -j ACCEPT
iptables -A OUTPUT -p tcp -s 202.54.1.20 --sport 3306 -d 202.54.1.50 --dport 1024

Where .20 is your MySQL and .50 is the remote connecting IP address.

Best Answer

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Mysql – Can’t start/stop thesql service

Mysql – Preventing brute-force attacks on MySQL

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