A tale of two burst balances (AWS EC2 and EBS performance)

Fri, 04 Sep 2020 18:17:46 +0000

When using and monitoring AWS for EC2 instances and their attached EBS volumes there are a couple of very important metrics to keep an eye on which can have enormous performance and availability implications. In particular I’m writing about General Purpose EC2 instance running in standard mode (eg. T2, T3 and T3a at the time of writing) and General Purpose EBS (gp2) because these are very common low-mid spec instances and the default disk storage type. If you’re already using one of the other EC2 or EBS types, chances are you’re already aware of some of the issues I’ll discuss below and those other products are designed to manage CPU and disk resources in a different load targeted way. These metrics are important because they report on the way these AWS resources (otherwise designed to mimic a real hardware) operate in a very different way. Note that while CPU credit reports are shown in the AWS web console for an EC2 instance under it’s Monitoring tab (and so people tend to see it), the EBS credit reports are not. To see these you need to find the EBS volume(s) attached to an EC2 instance (this is linked from the EC2 Description tab) and then look at the Monitoring tab for each EBS volume.

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A tale of two burst balances (AWS EC2 and EBS performance)