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Understand whats causing DataTransfer Cost (EC2 free service, tiny program)



I'm trying to understand whats causing DataTransfer costs in my program. After talking to AWS help, my EC2 instance (free tier) has apparently 'transferred' 13GB of data, however that doesn't make much sense to me.

My program:

3rd Party RSS Feed ---> AWS EC2 Server running 3 python scripts, manipulating data and publishes to database ---> MongoDatabase (not AWS hosted)

Whats weird to me, is that my Mongo Database is 4.44mb in total, so I dont understand how 13GB could have been transferred out of AWS. Is there a way for me to drill more into these costs so I can understand whats causing this data leak?

Any help is appreciated!

3 Answers

You can use Flow Logs with Athena to dig into your network traffic. Maybe you're polling the RSS feed too often.

answered 7 days ago
  • Thanks a lot - I am polling it a ton, but because it's fairly high frequency. Wouldn't that be 'data in' to AWS though? and not count towards this DataTransfer? (the rep I talked to told me it was only data out of AWS that counted)

  • You have to send the request out in order to get a response. Even small requests can add up if it's constantly polling.


VPC Flow Logs will capture the traffic going in and out of your instance and amount of bytes. Can also use Cloudwatch to monitor the traffic and set alarms for when the traffic goes above a certain threshold. "Data in" from the internet to AWS is not charged

answered 7 days ago

In addition to examining VPC flow logs to determine network outbound traffic (DTOs, data transfer out), you may also want to examine network inbound traffic in your MongoDB hosting environment. See if any packets are lost or blocked in your network. This may give you an answer why Mongo Database is still 4.44mb in total. If you would like to find out more details with regard to the data transfer costs in AWS, please refer to:

answered 6 days ago

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