We have a running redundant system onboard a vessel with very limited bandwidth (vsat), connected to 3 MySQL servers. Local, backup and remote. The remote SQL server is hosted in the AWS cloud. Both servers are always connected to all SQL servers.
As the connection goes down and varies a lot I made a gateway script running every 10 minutes checking the connection, disables is if not equal valid, and enables if status is disabled.
What we very often see is that the primary ignition server does not succeed in connecting, while the backup does. Still, on the MySQL client connections I can see two valid connections.
Is there a way to “disable” SQL connections on the secondary as long as primary is present?
Is there any recommendations regarding SQL connection parameters on such narrow band connections? I tried to play with time out etc, but is should be plenty. I can connect to the gateway interface and designer, but its slow.
The log tells me nothing about why it cant connect.