Explanation
Why the waste happens and who it affects.
For several resource types, a backup rule can move recovery points to a lower-cost cold storage tier after a set number of days, but the transition is optional and off unless the rule's lifecycle enables it. Monthly and yearly rules that keep backups for compliance, often for years, are frequently created without a cold storage transition, so recovery points that are almost never restored stay at warm storage rates for their whole retention period.
The price gap is large for the resource types that support it. In US East (Ohio), AWS Backup lists EFS backups at $0.05 per GB-month in warm storage versus $0.01 in cold storage, and DynamoDB backups at $0.10 versus $0.03. The backup plan documentation lists cold storage for AWS CloudFormation, DynamoDB with advanced features, Amazon EBS (through EBS Snapshots Archive), Amazon EFS, SAP HANA on EC2, Amazon Timestream and VMware virtual machines. RDS snapshots, Aurora cluster snapshots, FSx and S3 backups have no cold tier, so retention length is the only lever for them.
Billing model
The pricing dimensions that drive this cost.
AWS Backup bills the average backup storage consumed during the month, per GB-month, at a rate set by resource type and storage tier.
- Warm storage
- Default tier for every new recovery point, billed per GB-month at the higher rate
- Cold storage
- Lower per GB-month rate for supported resource types, with a minimum of 90 days in cold storage
- Cold storage minimum
- Total retention must be at least 90 days longer than the transition day, and the transition cannot be changed once a backup is cold
- EBS archive conversion
- EBS backups moved to cold storage go to EBS Snapshots Archive and become full, not incremental, copies
- Restore charges
- Restores are billed per GB restored, with separate rates for restores from cold storage
How to detect
5 checks to find it in your estate.
- Export backup plans with get-backup-plan and list rules whose Lifecycle has a long DeleteAfterDays (or none, meaning indefinite retention) but no MoveToColdStorageAfterDays
- Filter those rules to plans whose selections include EFS, DynamoDB with advanced features, EBS, Timestream, SAP HANA on EC2, VMware or CloudFormation resources
- List recovery points with list-recovery-points-by-backup-vault and check CalculatedLifecycle: recovery points with no MoveToColdStorageAt and a DeleteAt far in the future are long-lived warm backups
- Size the opportunity with BackupSizeInBytes per recovery point and the warm and cold rates for the resource type in the AWS Backup pricing table
- For EBS rules, check whether OptInToArchiveForSupportedResources is set, and whether the rule's frequency is monthly or less, which is when AWS Backup offers EBS archival
How to fix
5 ways to remove the waste.
- Enable Move backups from warm to cold storage on long-retention rules, keeping backups warm for at least 8 days as AWS Backup recommends, and set total retention at least 90 days beyond the transition
- Apply cold storage to monthly and yearly compliance rules rather than daily operational rules, since backups deleted or restored within 90 days of transition still pay the 90-day minimum
- For EBS, opt in to archival only for infrequent, long-retention backups, because archived EBS backups become full copies and can cost more than the incremental chain they replace
- Update existing long-lived recovery points with UpdateRecoveryPointLifecycle where appropriate, since changing the rule affects new recovery points
- Set explicit retention on every rule to the documented requirement instead of leaving it indefinite, and account for slower and costlier restores from cold storage in recovery plans
Documentation
Vendor references for pricing and configuration.