Explanation
Why the waste happens and who it affects.
These environments typically do not require high availability, yet still incur the full cost of redundant compute, storage, and data transfer. This results in unnecessary spend without operational benefit.
Billing model
The pricing dimensions that drive this cost.
EC2 is billed based on instance runtime and size, with additional charges for inter-AZ data transfer and supporting infrastructure (e.g., EBS volumes, load balancers). Spreading instances across Availability Zones does not by itself double instance count, but it can force extra minimum capacity (for example, at least one instance or NAT gateway per AZ) and adds inter-AZ data transfer charges, billed per GB in each direction.
How to detect
4 checks to find it in your estate.
- Review non-production Auto Scaling groups, subnets, and load balancers that span multiple Availability Zones
- Check for Auto Scaling Groups or load balancers distributing traffic across multiple Availability Zones
- Evaluate network transfer charges between Availability Zones
- Verify with workload owners whether fault tolerance is required for the environment
How to fix
3 ways to remove the waste.
- Reconfigure EC2 workloads in non-production environments to use a single Availability Zone
- Avoid distributing instances or traffic across multiple AZs unless justified by a specific requirement
- Establish environment-based architectural guidelines to limit Multi-AZ usage
Documentation
Vendor references for pricing and configuration.