Amazon EFS (Elastic File System) is a cloud-based file storage service for applications and workloads that run in the Amazon Web Services (AWS) public cloud.
AWS automatically deploys and manages the infrastructure for EFS, which is distributed across an unconstrained number of servers to avoid performance bottlenecks. Amazon EFS provides elastic storage capacity that scales to accommodate workloads that run on Elastic Compute Cloud (EC2) instances and access files through application programming interface (API) requests. An administrator interacts with EFS through its file system interface.
Amazon EFS is designed to be highly available and durable for thousands of EC2 instances that are connected to the service. Amazon EFS stores each file system object in multiple availability zones (AZs); an IT pro can access each file system from different AZs in the region it is located. The service also supports periodic backups from on-premises storage services to EFS for disaster recovery.
IT operations staff can mount an existing file system on an EC2 Linux instance to access it within Amazon EFS or administer a new file system from the AWS Management Console, AWS Command Line Interface, Amazon EFS API or AWS software development kits (SDKs). The Management Console, API and SDK also enable ops to delete systems and configure access and tags.
The NFSv4.1 protocol mounts an EFS system on an EC2 instance or an on-premises server to allow the service access to data and read and write to the file system. The Secure Copy feature transfers non-AWS hosted data to EFS. There must be an established cloud connection via AWS Direct Connect to access file systems on-premises.
The service includes file system access semantics, such as data consistency and file locks. An administrator controls access to the service through AWS Identity and Access Management roles and limits network access through Amazon Virtual Private Cloud security groups.
Amazon EFS includes default General Purpose performance mode and Max I/O performance mode. An admin can opt for the latter performance mode, which scales to higher throughput levels at the expense of latency for applications with many attached instances.
An AWS customer pays for the monthly GBs of file system storage that the service uses.