Explanation
Azure SQL databases often use the default backup configuration, which stores backups in RA-GRS storage to ensure geo-redundancy. While suitable for high-availability production systems, this level of resilience may be unnecessary for development, testing, or lower-impact workloads.
Using RA-GRS without a business requirement results in avoidable costs. Downgrading to LRS or ZRS - where appropriate - can significantly reduce monthly backup storage spend. This change has no impact on backup frequency or retention behavior, only the underlying storage replication method.
Relevant Billing Model
- Backup storage is charged based on GB/month
- RA-GRS storage is the default and most expensive option
- LRS (Locally Redundant Storage) and ZRS (Zone Redundant Storage) are lower-cost alternatives
- Changing backup storage tier can reduce backup costs by up to 50% without affecting primary database performance
Detection
- Review backup redundancy settings for Azure SQL databases
- Identify databases with RA-GRS enabled by default
- Determine whether geo-redundant backup storage is a business or compliance requirement
- Validate whether LRS or ZRS would be sufficient based on workload criticality and risk tolerance
Remediation
- For non-critical or non-regulated workloads, change the backup redundancy setting to LRS (or ZRS where supported)
- Document any exceptions where RA-GRS must be retained for compliance
- Incorporate backup configuration reviews into provisioning and governance processes
- Monitor backup storage cost trends following changes to confirm savings