When replicating an EFS file system across AWS regions (e.g., for disaster recovery), the destination file system does not automatically inherit the source’s lifecycle policy. As a result, files replicated to the destination will remain in the Standard storage class unless a new lifecycle policy is explicitly configured. Over time, this can lead to significantly higher storage costs, particularly in DR environments where data is rarely accessed but still replicated in full.

EFS offers lifecycle policies that transition files from the Standard tier to Infrequent Access (IA) based on inactivity, significantly reducing storage costs for cold data. When this feature is not enabled, infrequently accessed files remain in the more expensive Standard tier indefinitely. This often occurs when the file system is initially provisioned for performance but long-term access patterns are not reevaluated.

EFS file systems that are no longer attached to any running services — such as EC2 instances or Lambda functions — continue to incur storage charges. This often occurs after workloads are decommissioned but the file system is left behind. A quick indicator of this state is when the EFS file system has no mount targets configured. Without active usage or connection, these orphaned file systems represent pure cost with no functional value. Unlike block storage, EFS does not require an attached instance to incur billing, making it easy for unused resources to go unnoticed.