Amazon EFS Cheat Sheet 

• A fully-managed file storage service that makes it easy to set up and scale file storage in the Amazon Cloud.
• It is a serverless, set-and-forget, elastic file system that lets you share file data without provisioning or managing storage capacity.

Features

• 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 (NFSv4.1 and NFSv4.0) protocol.
• You can mount EFS filesystems onto EC2 instances running Linux or MacOS Big Sur and newer macOS versions. Windows is not supported.
• Aside from EC2 instances, you can also mount EFS filesystems on ECS tasks, EKS pods, and Lambda functions.
• 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 (for Standard classes) or within a single AZ (for One Zone classes).
• 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 AWS Backup.
• EFS supports Replication Failback, allowing you to synchronize changes from a destination file system back to the source, simplifying Disaster Recovery (DR) testing and failover/failback workflows.

Storage Classes and Lifecycle Management

• Amazon EFS Standard: For frequently accessed files stored across multiple AZs.
• Amazon EFS Infrequent Access (EFS IA): Cost-optimized for files accessed less frequently.
• Amazon EFS Archive: A new storage class optimized for long-lived data that is accessed a few times a year or less. It offers up to 50% lower cost than EFS IA.
• Amazon EFS One Zone: Stores data in a single AZ for frequently accessed data (lower cost, lower availability).
• Amazon EFS One Zone-IA: Stores data in a single AZ for infrequently accessed data.
• Lifecycle Management: EFS automatically moves files that have not been accessed for a set period (e.g., 7, 14, 30, 60, or 90 days) from Standard to IA, and  from IA to Archive.

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. Best for big data analysis, media processing, and genomic analysis.

Throughput Modes

• Elastic Throughput mode (recommended/default)
  • Throughput scales automatically with your workload activity, and you pay only for what you use. No provisioning required. Ideal for spiky or unpredictable workloads.
• Bursting Throughput mode 
  • Throughput scales as your file system grows (Now considered legacy/secondary to Elastic for most new use cases).
• 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
  file-system-id.efs.aws-region.amazonaws.com

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

Access Points

• EFS Access Points simplify how applications are provided access to shared data sets in an EFS file system. 
• EFS Access Points work together with AWS IAM and enforce an operating system user and group, and a directory for every file system request made through the access point. 

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.
• File systems created using the Amazon EFS console are automatically backed up daily through AWS Backup with a retention of 35 days. You can also disable automatic backups for your file systems at any time.
• Amazon CloudWatch Metrics can monitor your EFS file system storage usage, including the size in each of the EFS storage classes.

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.

Monitoring File Systems

• Amazon CloudWatch Alarms
• Amazon CloudWatch Logs
• Amazon CloudWatch Events
• AWS CloudTrail Log Monitoring
• Log files on your file system
• Use the PercentIOLimit metric to monitor IOPS utilization and ensuring you aren’t hitting the increased IOPS limits (up to 250,000 read IOPS and 50,000 write IOPS per file system).

Amazon EFS Security

• 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 can use AWS IAM to manage Network File System (NFS) access for Amazon EFS. You can use IAM roles to identify NFS clients with cryptographic security and use IAM policies to manage client-specific permissions.

Amazon EFS Pricing

• You pay only for the storage used by your file system.
• Pricing Specifics:
  • Storage: Charged per GB-month (Standard > IA > Archive).
  • Throughput:
    • Elastic Throughput: Pay for data read/written (GB transferred).
    • Provisioned Throughput: Pay for the throughput you provision (MB/s-month).
  • Data Access: Charges apply for reading from IA/Archive and for tiering data between classes.

EFS vs EBS vs S3

• Performance Comparison

• Performance Comparison

• Storage Comparison

Free Amazon EFS Tutorials on YouTube:

https://www.youtube.com/user/AmazonWebServices/search?query=EFS

Other Amazon EFS-related Cheat Sheets:

• Amazon S3 vs EBS vs EFS

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

Question 2

A company has an online stock exchange application with a daily batch job that aggregates all intraday data and stores the result to an existing Amazon EFS. Currently, the batch processing is handled by several On-Demand EC2 instances and takes less than 3 hours to complete to generate a report that will only be used internally in the company. The batch job can be easily and safely re-run in the event that there is a problem in the processing since the data being processed are not mission-critical. To further reduce its operating costs, the company is looking for ways to optimize its current architecture.

As the SysOps Administrator, which is the MOST cost-effective and secure solution that you should implement?

1. Request for a Spot Fleet to process the batch execution. Create a new EFS file system with encryption at rest enabled then copy all data from the current file system. After the data is copied over, delete the unencrypted file system. Use the new EFS file system when storing the results processed by the Spot instances.
2. Use Regional Reserved EC2 Instances to process the batch execution and register the instances to AWS Compute Optimizer to lower the costs further. Enable encryption at rest in the existing EFS file system.
3. Use Dedicated EBS-backed Amazon EC2 Instances to process the batch execution. Enable the Fast Snapshot Restore (FSR) feature on all EBS volumes to lower the storage cost. Create a new EFS file system with encryption at rest enabled then copy all data from the current file system. Use the new EFS file system when storing the results processed by the On-Demand instances.
4. Generate a custom AMI using the EC2 Image Builder service. Request for several Spot EC2 instances and launch your compute capacity using the AMI. Enable encryption at rest in the existing EFS file system. Create a rule in AWS Control Tower to automatically stop the EC2 instances after the batch processing.

For more AWS practice exam questions with detailed explanations, visit the Tutorials Dojo Portal:

Amazon EFS Cheat Sheet References:

https://docs.aws.amazon.com/efs/latest/ug/
https://aws.amazon.com/efs/pricing/
https://aws.amazon.com/efs/faq/
https://aws.amazon.com/efs/features/
https://aws.amazon.com/efs/when-to-choose-efs/