Amazon EFS
Amazon EFS is AWS's fully managed, serverless NFSv4.1 file system, GA since 2016 and mountable concurrently from thousands of EC2, ECS, EKS, Lambda, and on-prem clients. As of mid-2026 it ships three storage classes with Lifecycle Management auto-tiering between them: Standard ($0.30/GB-mo, ~1ms read/2.7ms write), Infrequent Access ($0.016/GB-mo regional), and Archive ($0.008/GB-mo, added Nov 2023) — Archive undercuts Standard by up to 97%. Default Elastic throughput mode bills $0.03/GB read plus $0.06/GB write and scales one file system to 20-60 GiBps (1,500 MiBps per client with EFS client v2+). Named production users on AWS's customer page include SiriusXM, Discover Financial Services, and Johnson & Johnson (37% cost cut via Lifecycle + One Zone). Current version/status: GA since 2016, continuously updated; Archive storage class added Nov 2023, Elastic Throughput made console default 2023-2024 (current as of July 2026). License: proprietary managed service (AWS). Pricing: Regional Standard $0.30/GB-mo; Infrequent Access $0.016/GB-mo; Archive $0.008/GB-mo (up to 97% cheaper than Standard, 50% cheaper than IA); Elastic throughput (default) adds $0.03/GB read + $0.06/GB write on top of storage; no minimum fee, 5GB free tier for 12 months. Maintained by Amazon Web Services (AWS).
Pick EFS when you need POSIX-compliant storage mounted read-write across dozens-to-thousands of EC2/ECS/EKS/Lambda instances at once — shared CMS uploads, or training data mounted by an autoscaling GPU fleet. Skip it for Windows-native shares: Azure Files' SMB + Active Directory integration beats EFS's NFS-only model, and for raw HPC throughput, FSx for Lustre or Google Filestore Zonal (up to 26 GiBps, 920K IOPS) outrun EFS's 20-60 GiBps ceiling. AWS's own docs concede Max I/O performance mode carries higher per-operation latency than General Purpose and shouldn't be used for new file systems — a legacy wart in a service AWS otherwise keeps current. Known weakness: AWS's own EFS performance docs admit Max I/O mode has higher per-operation latency than General Purpose and explicitly recommend against using it, yet it remains a selectable legacy option that can silently degrade a misconfigured file system.