Excessive Retention of Automated RDS Backups

Andrew Shieh

Service Category

Storage

Cloud Provider

AWS

Service Name

AWS RDS

Inefficiency Type

Retention

Explanation

If backup retention settings are too high or old automated backups are unnecessarily retained, costs can accumulate rapidly. RDS backup storage is significantly more expensive than equivalent storage in S3. For long-term retention or compliance use cases, exporting backups to S3 (e.g., via snapshot export to Amazon S3 in Parquet) is often more cost-effective than retaining them in RDS-native format.

Relevant Billing Model

Backups in RDS are billed by the total volume of backup data retained beyond the free tier (equal to the size of the active DB storage). Additional backup storage is charged per GB-month, which can lead to disproportionately high costs if backup volumes grow over time. Exporting snapshots to S3 offers a lower-cost archival alternative.

Detection

Review backup storage consumption by DB instance
Review total backup size versus DB size to identify excess retention
Check if automated backup retention periods are longer than necessary
Determine whether legacy snapshots are still required or can be deleted
Assess whether long-term backup needs could be satisfied with lower-cost S3 exports

Remediation

Adjust backup retention periods to match business or compliance needs
Delete outdated snapshots or unnecessary automated backups
Export long-term backups to S3 using snapshot export features
Monitor backup growth and align storage tier with data access needs

Relevant Documentation

https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/USER\_WorkingWithAutomatedBackups.html
https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/USER\_ExportSnapshot.html

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