The first step in troubleshooting the agent is finding out whether it is running or not. To do this see:
Some additional tips are:
To diagnose any issues with the agent, start by looking at the Logs link under the Settings tab, as described in Section 15.3, “Logs”. This page consolidates troubleshooting information across all the MySQL Enterprise Monitor components.
To run on start-up, the agent requires correct login
credentials for the monitored MySQL server. Log in to the
monitored MySQL server and check the agent's credentials.
Compare the values of the
User fields in the
mysql.user table with the values shown in
file. The passwords are encrypted so they can not be manually
managed here, but the password can be altered from the
MySQL Instances page in the
MySQL Enterprise Monitor User Interface, or by using the agent connection tool
agent.sh) from the command line.
The agent will fail to start up if incorrect credentials are specified for the service manager login. Using incorrect credentials for logging in to the service manager creates an entry in the agent log file. For the location of this log file see Section D.2.2, “Agent Log Files”.
An easy way to confirm that the agent can log in to the
service manager is to type
into the address bar of your web browser, substituting the
appropriate host name and port. When the HTTP authentication
dialog box opens, enter the agent user name and password. The
following message indicates a successful login:
<exceptions> <error>E0401: NullAgentPayloadException: </error> </exceptions>
Despite the fact that the preceding listing shows an error, you have logged in successfully. This error appears because you have logged in but with no “payload”.
If you can log in successfully in the way described above and
the agent is running, then there may be errors in Agent's
configuration. Compare the host name, port, agent name, and
password used in the MySQL Enterprise Monitor User Interface, and also check it using
agent.sh, with the values you entered
into the address bar of your web browser.
If HTTP authentication fails then you are using incorrect credentials for the agent. Attempting to log in to the service manager using incorrect credentials creates an entry in the agent log file. For the location of this log file see Section D.2.2, “Agent Log Files”.
If no HTTP authentication dialog box appears, and you are
unable to connect at all, then the host name or port might be
specified incorrectly. Confirm the values you entered against
those described as the
Application hostname and
port: in the
configuration_report.txt file. Failure to
connect could also indicate that the port is blocked on the
machine hosting the MySQL Enterprise Service Manager.
To check if a blocked port is the problem, temporarily bring down your firewall. If the agent is then able to connect, open up the port specified during installation and restart the agent. If necessary you can monitor outside the firewall using an SSH tunnel. For more information, see Section 5.11, “Monitoring Outside the Firewall with an SSH Tunnel”.
Running the agent from the command line sometimes displays errors that fail to appear in the log file or on the screen when the agent is started from a menu option. To start the agent from the command line see the instructions given at the start of this section.
If you have more than one agent running on the same machine,
UUID must be unique.
If the agent and the MySQL server it is monitoring are running
on different machines, ensure that the correct
host is specified for the agent account.
The correct port, typically 3306, must also be open for remote
login. For more information about remote monitoring see,
Section 5.10, “Configuring an Agent to Monitor a Remote MySQL Server”.
The MySQL Enterprise Monitor Agent and MySQL Enterprise Service Manager use the unique host ID,
stored within the
mysql.inventory table on
the monitored MySQL Server, to determine whether the instance
being monitored is a clone. The host ID of the current server
is checked against the stored value when the agent starts. If
the generated host ID and stored host ID do not match, you get
an error similar to the following in the agent log file:
%s: [%s] the hostid from mysql.inventory doesn't match our agent's host-id (%s != %s) We assume that this is a cloned host and shutdown now. Please TRUNCATE TABLE mysql.inventory on this mysql-instance and restart the agent. If this is a master for replication, please also run SET SQL_LOG_BIN = 0; first.
To fix the problem, connect to the MySQL server using the
credentials configured when you installed the agent, and then
mysql> TRUNCATE mysql.inventory;
Now restart the agent, which recreates the
mysql.inventory table with the updated
instance UUID and hostid information.