When file systems are launched with Provisioned Throughput, teams often overestimate future demand — especially in environments cloned from production or sized “just to be safe.” Over time, many workloads consume far less throughput than allocated, especially in dev/test environments or during periods of reduced usage. These overprovisioned settings can silently accrue substantial monthly charges that go unnoticed without intentional review.
This inefficiency is not flagged by AWS Trusted Advisor and is easy to miss. Elastic Throughput mode now offers a scalable alternative that automatically adjusts capacity — but isn’t always cheaper, depending on the workload’s sustained throughput.
Amazon EFS supports three throughput modes:
Bursting Throughput Mode – Default option for General Purpose file systems. Throughput automatically scales with the amount of storage; short bursts above the baseline are supported using a credit system. No separate throughput charge.
Provisioned Throughput Mode – Throughput is explicitly configured in MB/s and billed separately from storage, regardless of actual usage.
Elastic Throughput Mode – Throughput scales automatically to meet demand and is billed based on actual usage above the baseline included with storage.
Provisioned throughput is billed continuously, even if the application’s actual throughput is far below the configured amount. Elastic mode eliminates this fixed cost but can be more expensive if workloads regularly exceed the baseline.
