Administering Command Center Agents
The Command Center metrics collection agent,
ccagent, runs on segment hosts and receives real-time metrics emitted by the metrics collection database extension. Each segment host has one
ccagent process. The metrics collection extension connects to
ccagent using Unix Domain Sockets (UDS) to transfer metrics from Greenplum Database. Starting Greenplum Command Center with the
gpcc start command starts the Command Center agent on each segment host. Stopping Command Center with
gpcc stop ends these processes. The Command Center backend monitors these agents and restarts them when necessary.
This topic describes basic agent administration tasks, including enabling agents after adding hosts to the cluster and viewing the agent log files.
The Greenplum Database
gpperfmon_install utility enables the
gpsmon data collection agents. Greenplum Command Center no longer requires the history data these agents collect. You can run the gpperfmon data collection agents and the Command Center metrics collection agents in parallel, but unless you need the data the gpperfmon agents collect for some other purpose, you can improve the Greenplum Database system performance by disabling the gpperfmon agents.
To see if the gpperfmon agents are enabled, check the
gp_enable_gpperfmon server parameter with the following command.
$ gpconfig -s gp_enable_gpperfmon
gp_enable_gpperfmon parameter is on, disable the agents by setting the parameter to off and restarting Greenplum Database.
$ gpconfig -c gp_enable_perform -v off $ gpstop -ar
For more information about the gpperfmon data collection agents see
gpperfmon_install in the Greenplum Database Utility Reference.
The metrics collection agent
ccagent runs queries on Greenplum Database on behalf of Command Center to perform activities such as retrieving information to display in the Command Center UI, saving state in the gpperfmon and postgres databases, inserting alert event records, and harvesting query history for the gpmetrics history tables. The agent runs these queries using the gpmon database role.
If you do not want all of this query activity to be logged in the
pg_log log file, you can set logging options for the gpmon role using the
ALTER ROLE command. For example, these commands set the gpmon role to log only DDL statements (
DROP) and to log only fatal and panic errors.
ALTER ROLE gpmon SET log_statement TO DDL; ALTER ROLE gpmon SET log_min_messages to FATAL;
When you add or replace Greenplum Database hosts, you must reinstall the Greenplum Command Center software to ensure the software is installed on the new hosts. It is not necessary to uninstall Command Center before reinstalling.
Log messages for the Command Center metrics collector agents are saved in the
logs directory of the Command Center installation directory on the master and each segment host.
The current log file is named
agent.log. When a new log is started, the current log is renamed to
agent.<timestamp>.log and a new
agent.log file is opened. You should remove old log files regularly to recover space.