Instability in RDS MySQL db after increasing storage space

It's highly unlikely your problems are associated with the increase in storage size. That you increased max_connections is more of a hint to me as it suggests you are driving the t2.micro harder and perhaps beyond what its limited memory can support. Also remember you have the CPU burst balance to deal with. All database systems are subject to some level of instability if you push them too far beyond the resource limits, and I believe MySQL is one of the worst offenders. You might want to do some performance analysis to see what is going on.

On the connectivity front it sounds like the application does not properly handle connections dying. It should be getting an error and re-connecting.

Thanks a lot! This clarified a couple things for sure. It was helpful.

We had reset max_connections parameter value to its default value soon after we posted the question. Therefore, yesterday was a better day, once again. There was a very brief period when our app maxed on DB connections, but it recovered immediately. It was such a relief!

The reconnecting logic could be tricky when the system is already saturated. We will figure this out.

This is just to inform that the RDS instance has been stable as it used to be in the past. All that we did was to reset max_connections parameter. Little did I know it would cause such stress, panic and havoc.