MySql server PID not found - mysql

Question

I have CentOS 6.4 with NGINX.
When I try to start/stop/restart mysql server (/etc/init.d/mysqld restart) I get this error:
MySQL server PID file could not be found! [FAILED]
Starting MySQL..The server quit without updating PID file ([FAILED]/mysql/mysqld.pid).
What can I do to solve this problem?
Thanks!

Answer 1

I got the same error on a CentOS 6.3 where I upgraded MySQL to 5.6.14 but I kept the old my.cnf file. After upgrade, MySQL did not start anymore, giving me the same error as you described.
The problem was that I had this setting in my.cnf:
table_cache=2048
According to this link table_cache renamed table_open_cache..
"Seem like in 5.5 the system variable table_cache was renamed
table_open_cache..
In 5.6 mysqld fails if it finds an unknown variable
this means that upgrades from versions earlier than 5.5 can have
problems if table_cache is specified in my.cnf."
After I changed the above line to
table_open_cache=2048
MySQL started perfectly.
So, in the case you have MySQL 5.5+ (and maybe an older my.cnf), I suggest you to do the following:
remove my.cnf from /etc folder and try to start MySQL
if MySQL starts, the the problem is in my.cnf. Comment/uncomment all the settings one by one in order to see which is causing the problem.
Hope this helps.

Answer 2

I upgraded my Mac OS to 10.9.3 and encountered the above problem on mysql.server restart
The following fixed my problem
sudo chmod -R o+rwx /usr/local/var/mysql/
sudo chown -R mysql /usr/local/var/mysql/
sudo mysql.server restart

Answer 3

First of all make sure that which folder/file is not exist in /var/run/mysqld/mysqld.pid
if dir not exists then create it as:
sudo mkdir -p /var/run/mysqld/
if mysqld.pid is not exists then create it as:
sudo touch /var/run/mysqld/mysqld.pid
change ownership as:
sudo chown mysql:mysql -R /var/run/mysqld
chmod 775 -R /var/run/mysqld
restart mysql service
sudo service mysql restart

Answer 4

I find that sometimes MySQL processes are still running. Certainly this was the case on my OS X Yosemite system so use the following command to find any processes that show up with MySQL in the name:
ps aux | grep mysql
Then kill them using the command
sudo kill -9 PID, replacing PID with the offending process ID.

Answer 5

Check if there is a lock.
/etc/init.d/mysql status
If the OS says that there is a lock, something like:
ERROR! MySQL is not running, but lock file (/var/lock/subsys/mysql) exists
remove that lock file and restart.

Answer 6

I found this worked....
# ps aux | grep mysql
root 3668 0.0 0.0 11432 1240 ? S 2014 0:00 /bin/sh /usr/bin/mysqld_safe --datadir=/db/data01 --pid-file=/var/lib/mysql/mysql.pid
mysql 5303 0.1 0.4 1964748 12368 ? S<l 2014 1663:35 /usr/sbin/mysqld --basedir=/usr --datadir=/db/data01 --plugin-dir=/usr/lib64/mysql/plugin --user=mysql --log-error=/db/logs01/mysql-error.err --open-files-limit=8192 --pid-file=/var/lib/mysql/mysql.pid --socket=/var/lib/mysql/mysql.sock --port=3306
root 12369 0.0 0.0 6376 680 pts/0 S+ 09:05 0:00 grep mysql
# kill -9 3668 5303
# rm /var/lock/subsys/mysql rm: remove regular empty file `/var/lock/subsys/mysql'? y
# service mysql start Starting MySQL (Percona Server).. SUCCESS!