Data_engine restarts continuously and eventually turns red (goes into an error state). You will observe the following error in the logs:
error: Open: Too many connections (errno:1040)
Eventually the probe will either show Error, or appear to be in a reboot loop showing a new port and /or PID, depending on how quickly it restarts.
MySQL 5.x database supporting UIM 7.x or higher
Connection limit defaults on MySQL are often too low for enterprise-level applications. The data_engine opens numerous connections to facilitate simultaneous inserts, reading and maintenance of data.
This problem is exacerbated by setting up data_engine multi-threading (by setting keys such as thread_count_insert = 3 and queue_limit_total = 100000); the Primary Hub can open enough connections to nearly saturate MySQL. Combined with other robots opening database connections (UMP especially) then the connection limit will be hit and data_engine will be impacted.
Edit the MySQL startup configuration file (my.cnf) and increase the max_connections.
1. This can be found in different places depending on the installation method of mysql. For reference, default options are read from the following files in the given order:
Or, on Windows:
C:\Program Files\MySQL\MySQL Server 5.6my.ini
C:\Program Files\MySQL\MySQL Server 5.6\my.cnf
C:\ProgramData\MySQL Server 5.6\my.cnf
2. Next, change the value of max_connections to a higher value. 500 is a good place to start but it will vary depending on the environment and the amount of data being collected. You may need to increase this even further until you find a level that eliminates the error message.
3. Finally, restart data_engine. If other probes such as nis_server, udm, discovery, and wasp are encountering issues, restart those probes (or the entire robot) which should allow the probes to retry the mysql connection once again.
See your MySQL user manual for more information about connection limits.