6

I am using new relic to monitor the performance of my server. Recently I noticed a very strange problem where for every 3 hours, the server will be down for 1 minute. And in the new relic report, during the server down time, there were sudden spike on the database.

The problem is I am new in system admin, I don't know how to view the database log. I am using Mariadb on a Ubuntu 14.04 machine. So, where can I find the log? I tried to view in /var/log/mysql.err, /var/log/mysql.log and /var/log/mysql/error.log there are no content inside.

I also tried grep 'mysql' /var/log/syslog, nothing found as well.

Do I need to enable the logging in mariadb config file? If so, how?

7

One of the ways to find out your current log file path is using the following SQL query:

show global variables like 'log_error';

The output should look something like this:

+---------------+---------------------+
| Variable_name | Value               |
+---------------+---------------------+
| log_error     | /var/log/mysqld.log |
+---------------+---------------------+
  • it shows /var/log/mysql/error.log, but no content in the log. I also try show global variables like 'log'; It show log : OFF, seem the loggin is turned off. How do I enable it? – dev-jim Nov 22 '15 at 6:25
  • 1
    No, log variable is related to general query logging. It could be that MySQL doesn't have privileges to write in /var/log/mysql/error.log. Can you check the current permissions and ownership by running ls -la /var/log/mysql/error.log? Your MySQL server is most probably running under "mysql" user, so it would make sense to change permissions and ownership with sudo chown mysql.root /var/log/mysql/error.log && sudo chmod 640 /var/log/mysql/error.log – Tubeless Nov 22 '15 at 11:40
1

I had the same issue on Debian 8.5, using MariaDB 10.1.16. I put the configuration as recommended but nothing, there was no way that the error.log file was written with the errors.

At the end, look in / var / log / syslog and there were the errors and warnings

tail -f /var/log/syslog | grep mysql

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