> For the complete documentation index, see [llms.txt](https://karansingh.gitbook.io/aws-saa-c02/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://karansingh.gitbook.io/aws-saa-c02/ec2-storage-ebs-efs-instance-store/elastic-file-system-efs.md).

# Elastic File System (EFS)

## Overview

* Amazon **EFS provides a simple, scalable, fully managed elastic NFS file system** for use with AWS Cloud services and on-premises resources.<br>

* It is **built to scale on demand to petabytes without disrupting applications, growing and shrinking automatically** as you add and remove files.<br>

* **The service manages all the file storage infrastructure for you**, meaning that you can avoid the complexity of deploying, patching, and maintaining complex file system configurations.

* Amazon **EFS supports the Network File System version 4 (NFSv4.1 and NFSv4.0) protocol.**
  * **EFS only supports Linux instances**.<br>

* **Multiple Amazon EC2 instances can access an Amazon EFS file system at the same time**, providing a common data source for workloads.

## Storage Classes

* Amazon **EFS offers two storage classes, Standard and Infrequent Access**.
  * The **Standard storage class is used to store frequently accessed files**.<br>
  * The **Infrequent Access (IA) storage class is a lower-cost storage class that's designed for storing long-lived, infrequently accessed files** cost-effectively.<br>
* Amazon **EFS file systems store data and metadata across multiple Availability Zones in an AWS Region**.

## Lifecycle management <a href="#lifecycle-management-efs" id="lifecycle-management-efs"></a>

* Lifecycle management **automatically manages cost-effective file storage for your file systems**.<br>
* When enabled, lifecycle management **migrates files that have not been accessed for a set period of time to the Infrequent Access (IA) storage class**.
  * You **define that period of time by using a lifecycle policy***.*<br>
* **After lifecycle management moves a file into the IA storage class, the file remains there indefinitely**.<br>
* Lifecycle management **applies to all files in the file system**.

## Performance Modes

* **General Purpose Performance Mode:**
  * **Recommended for the majority** of your Amazon EFS file systems.<br>
  * General Purpose is **ideal for latency-sensitive** use cases, like **web serving environments, content management systems, home directories, and general file serving**.<br>
  * EFS selects the General Purpose mode for you by **default**.<br>
* **Max I/O Performance Mode:**
  * File systems in the Max I/O mode **can scale to higher levels of aggregate throughput and operations per second**.<br>
  * This scaling is done with a trade-off of **slightly higher latencies for file metadata operations**.<br>
  * Highly parallelized applications and workloads, such as **big data analysis, media processing, and genomics analysis**, can benefit from this mode.