Unexpected WriteCapacityUnit-Hrs for DynamoDB

Question

Hello, there was a DynamoDB instance I deployed for testing purpose and been idle for a couple a days.
But why there are consistency WriteCapacityUnit-Hrs (while I'm doing nothing) in every day as described below? Why there is an additional cost?

Aug-01* - 0.00 WriteCapacityUnit-Hrs
Aug-02* - 0.00 WriteCapacityUnit-Hrs
Aug-03* - 0.00 WriteCapacityUnit-Hrs
Aug-04* - 0.00 WriteCapacityUnit-Hrs
Aug-05* - 0.00 WriteCapacityUnit-Hrs
Aug-06* - 0.00 WriteCapacityUnit-Hrs
Aug-07* - 1,200.00 WriteCapacityUnit-Hrs
Aug-08* - 7,200.00 WriteCapacityUnit-Hrs
Aug-09* - 7,200.00 WriteCapacityUnit-Hrs
Aug-10* - 7,200.00 WriteCapacityUnit-Hrs
Aug-11* - 7,200.00 WriteCapacityUnit-Hrs
Aug-12* - 7,200.00 WriteCapacityUnit-Hrs
Aug-13* - 7,200.00 WriteCapacityUnit-Hrs

Tan · Answer

Thank you for your reply.

I figured out this note in the [AWS DMS DynamoDB userguide](https://docs.aws.amazon.com/dms/latest/userguide/CHAP_Target.DynamoDB.html):
"When AWS DMS sets DynamoDB parameter values for a migration task, the default Read Capacity Units (RCU) parameter value is set to 200."

I indeed skipped this note when deploying the services. But I'm really socked that the default RCU and WCU are set this high (200 by default). Forget to teardown the resources for a couple of days meant for testing purpose can lead into this situation though...

Didier_Durand · Answer

Hi,

Those costs very probably occur because you've configured some provisioned capacity which is charged independently of your effective activity: https://aws.amazon.com/dynamodb/pricing/provisioned/

You have to switch back to on-demand standard mode to erase those costs: https://aws.amazon.com/dynamodb/pricing/on-demand/

Best,

Didier

Unexpected WriteCapacityUnit-Hrs for DynamoDB

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