EFS - Elastic File System

Table of contents

• General
• Performance
  • Performance Mode
    • General Purpose
    • Max I/O
  • Throughput Mode
    • Bursting
    • Provisioned
    • Elastic
• Storage Classes

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General

• It is a managed Network file system (NFS), but differently from the EBSs, they work on multiple AZs and must be set inside of a VPC Security Group for access control.
• More expensive than EBS, but it is paid per use. No capacity provisioning here - file system will scale automatically.
• Highly available (multi-AZ) and highly scalable.
• Files are encrypted at rest with KMS.
• An EFS may be attached to multiple EC2 instances and an instance may have multiple EFSs attached to it.
• Uses NFSv4.1 protocol.
• Recommended for web serving, data management/sharing, etc.
• They are only compatible with Linux-based images. No compatibility with Windows images.
• AWS Lambda can integrate with EFS.

Performance

It is possible to set the Performance Mode and the Throughput Mode.

Performance Mode

Performance Mode is set the EFS creation time and can be:

General Purpose

• Default mode for EFS. This is the recommended mode by AWS for all file systems.
• Recommended for latency-sensitive scenarios such as web serving.

Max I/O

• Higher throughput and parallelism capabilities, but also higher latency.
• Recommended for Big data processing, media processing etc.
• Not compatible with Elastic throughput mode as the throughput scales automatically in that mode.

Throughput Mode

There are three types of Throughput mode:

Bursting

• Throughput that scales with the amount of storage in your file system.

Provisioned

• Throughput is set by you.
• Recommended when you know how will be your wokload requirements.

Elastic

• Recommended mode by AWS.
• Scales with the workload in your file system. Recommended when there are spiky or unpredictable workloads.

Storage Classes

There are four different storage class and files on a single EFS can be on diffent tiers (IA or non-IA). It is also possible to set Lifecycle management rules. The classes are:

• EFS Standard: Data is replicated across multiple AZs. Ideal for frequently accessed files.
• Standard IA: Infrequent access. There are lower storage cost, but file retrieval is paid.
• EFS One Zone : Data is replicated within a single AZ. Suitable for development environment. Not suitable for production environment.
• EFS One Zone IA: over 90% cheaper than the rest.