Amazon EFS

  • A fully-managed file storage service that makes it easy to set up and scale file storage in the Amazon Cloud.


  • The service manages all the file storage infrastructure for you, avoiding the complexity of deploying, patching, and maintaining complex file system configurations.
  • EFS supports the Network File System version 4 protocol.
  • Multiple Amazon EC2 instances can access an EFS file system at the same time, providing a common data source for workloads and applications running on more than one instance or server.
  • EFS file systems store data and metadata across multiple Availability Zones in an AWS Region.
  • EFS file systems can grow to petabyte scale, drive high levels of throughput, and allow massively parallel access from EC2 instances to your data.
  • EFS provides file system access semantics, such as strong data consistency and file locking.
  • EFS enables you to control access to your file systems through Portable Operating System Interface (POSIX) permissions.
  • Moving your EFS file data can be managed simply with AWS DataSync – a managed data transfer service that makes it faster and simpler to move data between on-premises storage and Amazon EFS.
  • You can schedule automatic incremental backups of your EFS file system using the EFS-to-EFS Backup solution.
  • Amazon EFS Infrequent Access (EFS IA) is a new storage class for Amazon EFS that is cost-optimized for files that are accessed less frequently. Customers can use EFS IA by creating a new file system and enabling Lifecycle Management. With Lifecycle Management enabled, EFS automatically will move files that have not been accessed for 30 days from the Standard storage class to the Infrequent Access storage class.

Performance Modes

  • General purpose performance mode (default)
    • Ideal for latency-sensitive use cases.
  • Max I/O mode
    • Can scale to higher levels of aggregate throughput and operations per second with a tradeoff of slightly higher latencies for file operations.

Throughput Modes

  • Bursting Throughput mode (default)
    • Throughput scales as your file system grows.
  • Provisioned Throughput mode
    • You specify the throughput of your file system independent of the amount of data stored.

Mount Targets

  • To access your EFS file system in a VPC, you create one or more mount targets in the VPC. A mount target provides an IP address for an NFSv4 endpoint.
  • You can create one mount target in each Availability Zone in a region.
  • You mount your file system using its DNS name, which will resolve to the IP address of the EFS mount target. Format of DNS is

AWS Training Amazon EFS

  • When using Amazon EFS with an on-premises server, your on-premises server must have a Linux based operating system.

Components of a File System

  • ID
  • creation token
  • creation time
  • file system size in bytes
  • number of mount targets created for the file system
  • file system state
  • mount target

Data Consistency in EFS

  • EFS provides the open-after-close consistency semantics that applications expect from NFS.
  • Write operations will be durably stored across Availability Zones.
  • Applications that perform synchronous data access and perform non-appending writes will have read-after-write consistency for data access.

Managing File Systems

  • You can create encrypted file systems. EFS supports encryption in transit and encryption at rest.
  • Managing file system network accessibility refers to managing the mount targets:
    • Creating and deleting mount targets in a VPC
    • Updating the mount target configuration
  • You can create new tags, update values of existing tags, or delete tags associated with a file system.
  • The following list explains the metered data size for different types of file system objects.
    • Regular files – the metered data size of a regular file is the logical size of the file rounded to the next 4-KiB increment, except that it may be less for sparse files.
      • A sparse file is a file to which data is not written to all positions of the file before its logical size is reached. For a sparse file, if the actual storage used is less than the logical size rounded to the next 4-KiB increment, Amazon EFS reports actual storage used as the metered data size.
    • Directories – the metered data size of a directory is the actual storage used for the directory entries and the data structure that holds them, rounded to the next 4 KiB increment. The metered data size doesn’t include the actual storage used by the file data.
    • Symbolic links and special files – the metered data size for these objects is always 4 KiB.
  • File system deletion is a destructive action that you can’t undo. You lose the file system and any data you have in it, and you can’t restore the data. You should always unmount a file system before you delete it.
  • You can use AWS DataSync to automatically, efficiently, and securely copy files between two Amazon EFS resources, including file systems in different AWS Regions and ones owned by different AWS accounts.  Using DataSync to copy data between EFS file systems, you can perform one-time migrations, periodic ingest for distributed workloads, or automate replication for data protection and recovery.

Mounting File Systems

  • To mount your EFS file system on your EC2 instance, use the mount helper in the amazon-efs-utils package.
  • You can mount your EFS file systems on your on-premises data center servers when connected to your Amazon VPC with AWS Direct Connect or VPN.
  • You can use fstab to automatically mount your file system using the mount helper whenever the EC2 instance is mounted on reboots.

Lifecycle Management

  • You can choose from four EFS Lifecycle Management policies (14, 30, 60, or 90 days) to automatically move files into the EFS Infrequent Access (EFS IA) storage class and save up to 85% in cost.

Monitoring File Systems

  • Amazon CloudWatch Alarms
  • Amazon CloudWatch Logs
  • Amazon CloudWatch Events
  • AWS CloudTrail Log Monitoring
  • Log files on your file system


  • You must have valid credentials to make EFS API requests, such as create a file system.
  • You must also have permissions to create or access resources.
  • When you first create the file system, there is only one root directory at /. By default, only the root user (UID 0) has read-write-execute permissions.
  • Specify EC2 security groups for your EC2 instances and security groups for the EFS mount targets associated with the file system.


  • You pay only for the storage used by your file system.
  • Costs related to Provisioned Throughput are determined by the throughput values you specify.


  • Performance Comparison

Amazon EFS

Amazon EBS Provisioned IOPS

Per-operation latency

Low, consistent latency.

Lowest, consistent latency.

Throughput scale

10+ GB per second.

Up to 2 GB per second.

  • Storage Comparison

Amazon EFS

Amazon EBS Provisioned IOPS

Availability and durability

Data is stored redundantly across multiple AZs.

Data is stored redundantly in a single AZ.


Up to thousands of EC2 instances, from multiple AZs, can connect concurrently to a file system.

A single EC2 instance in a single AZ can connect to a file system.

Use cases

Big data and analytics, media processing workflows, content management, web serving, and home directories.

Boot volumes, transactional and NoSQL databases, data warehousing, and ETL.




Default Limit

Number of file systems for each customer account in an AWS Region


Number of mount targets for each file system in an Availability Zone in a Region


Number of mount targets for each VPC in a Region


Number of security groups for each mount target


Number of VPCs for each file system


Maximum size of a single file

47.9 TiB


Free Amazon EFS Tutorials on YouTube:

Other Amazon EFS-related Cheat Sheets:


Validate Your Knowledge

Question 1

A multinational company has been building its new data analytics platform with high-performance computing workloads (HPC) which requires a scalable, POSIX-compliant storage service. The data need to be stored redundantly across multiple AZs and allows concurrent connections from thousands of EC2 instances hosted on multiple Availability Zones.

Which of the following AWS storage service is the most suitable one to use in this scenario?

  1. EBS Volumes
  2. Elastic File System
  3. Amazon S3
  4. ElastiCache

Correct Answer: 2

In this question, you should take note of this phrase: “allows concurrent connections from multiple EC2 instances”. There are various AWS storage options that you can choose but whenever these criteria show up, always consider using EFS instead of using EBS Volumes which is mainly used as a “block” storage and can only have one connection to one EC2 instance at a time.

Amazon EFS is a fully-managed service that makes it easy to set up and scale file storage in the Amazon Cloud. With a few clicks in the AWS Management Console, you can create file systems that are accessible to Amazon EC2 instances via a file system interface (using standard operating system file I/O APIs) and supports full file system access semantics (such as strong consistency and file locking).

Amazon EFS file systems can automatically scale from gigabytes to petabytes of data without needing to provision storage. Tens, hundreds, or even thousands of Amazon EC2 instances can access an Amazon EFS file system at the same time, and Amazon EFS provides consistent performance to each Amazon EC2 instance. Amazon EFS is designed to be highly durable and highly available.


For more AWS practice exam questions with detailed explanations, check this out:Tutorials Dojo AWS Practice Tests




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