MySQL logs at tmpfs

mysql logs at tmpfs

MySql logs at tmpfs

I updated my Ubuntu to version 16.04 recently. The update process was successfull for all products except MySQL. MySQL 5.7 finished every try to install it with error. So I had to fully uninstall the previous version of MySQL. MySQL 5.7 was installed successfully at my desktop just after that.

Good! I worked effectively a whole day with new version of Ubuntu, PHP 7.0 and MySQL 5.7.

What large surprize it was for me when I discovered next morning that MySQL service can not be started. Moreover it said nothing about the reason except:


Job for mysql.service failed because the control process exited with error code.
See “systemctl status mysql.service” and “journalctl -xe” for details.

and with more details but still useless:

— Unit mysql.service has begun starting up.
May 03 14:59:18 eagle systemd[1]: mysql.service: Main process exited, code=exited, status=1/FAILURE

I spent a lot of time trying to find and isolate a reason of such MySql failure. I fully reinstalled MySQL few times. I even tried a MariaDB fork. But every time I finished with the same result. Database server worked fine after its installation, but failed to start at once after the 1st reboot.
What’s the difference? I found myself at the state near to a dead lock. Dead Lock! 1 hour, 2 hours, 3 hours…


Thanks to SOMEONE who turned that light at my head. I remembered that I use temporary file system mapped to the memory for the system logs and other temporary files.

Filesystem 1K-blocks Used Available Use% Mounted on
tmpfs 8193016 1428 8191588 1% /var/log
tmpfs 8193016 33952 8159064 1% /tmp

The only difference with tmpfs at RAM is that it’s absolutely clear after system reboot. And this difference may be a reason of MySQL start failure.
I compared tmpfs type folders before and after reboot and discovered that system does not creates /var/log/mysql folder automatically, as other services do, Apache, for example. When I created /var/log/mysql folder manually, MySQL was started from a command line successfully.

The next task I had to resolve how to force my system create /var/log/mysql folder every time after system reboot, but before MySQL server start. So let’s finish with lyrics and return to the subject of this post. I took an idea from this post. Finally a solution is:

1) Create the file /etc/init.d/mysql-logs
with this content

# Provides:          mysql-logs
# Default-Start:     2 3 4 5
# Default-Stop:      0 1 6
# Required-Start:    
# Required-Stop:     
# Short-Description: Create the mysql work environment at startup 
# Description:       Create the /var/log/mysql
# main()
case "${1:-''}" in
   #create the /var/log/mysql
   mkdir -p /var/log/mysql
   chown mysql:root /var/log/mysql  
   echo "Usage: $SELF start|stop"
   exit 1

2) Declare it for startup (S18) & shutdown (K22)

$ sudo update-rc.d mysql-logs defaults 18 22

You made it. Just reboot and look at working MySQL.