Is db.t3.medium run in unlimited mode?

Question

We're inserting a lot of records into the RDS. During the process, we observed that the CPU utilization is throttled down to 10% after running out the CPU credit balance.  
  
Here's the Cloudwatch metrics:  
https://imgur.com/a/P4RGTdM  
  
The insert operations started at around 16:00. The CPU usage was around 100% at the beginning but throttled to 10% at around 18:30. The same moment that we're about to run out of the burst balance.  
  
According to the AWS document  :  
"Amazon RDS T3 instances are configured for Unlimited mode, which means they can burst beyond the baseline over a 24-hour window for an additional charge."  
  
The RDS t3 instance should be running in "unlimited mode", which should not throttle the CPU usage but charge an additional CPU fee instead when running out the credits?

Answer

We can observe the "Write IOPS" got throttled down to 100 IOPS at the same.  
https://imgur.com/a/YFCsKKr  
  
So I guess the bottleneck is disk, not CPU.  
  
Thank you for the clarification.

Answer

Yes, t3 uses unlimited CPU credits. Burst Balance is a measure of the gp2 volume burst usage, not related to CPU.  
  
https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/monitoring-cloudwatch.html  
  
https://aws.amazon.com/blogs/database/understanding-burst-vs-baseline-performance-with-amazon-rds-and-gp2/  
  
hth,   
-Phil

Is db.t3.medium run in unlimited mode?

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