EFS - Elastic File System

• EFS is a managed NFS (network file system) that can be mounted on many EC2 instances
• EFS works with EC2 instances across multi AZs
• EFS is highly available, scalable, but also more expensive (3x GP2) than EBS
• EFS is pay per use
• Use cases: content management, web service, data sharing, Wordpress
• Uses NFSv4.1 protocol
• We can use security groups to control access to EFS volumes
• EFS is only compatible with Linux based AMIs (not Windows)

EFS Performance and Storage Classes

• EFS Scale
  • Thousands of concurrent NFS clients, 10 GB+ per second throughput
  • It can grow to petabyte scale NFS automatically
• Performance mode (can be set at EFS creation time)
  • General purpose (default): recommended for latency-sensitive use cases: web server, CMS, etc.
  • Max I/O - higher latency, throughput, highly parallel, recommended for big data, media processing
• Storage tiers: lifecycle manage feature
  • Standard: for frequently accessed files
  • Infrequent access (EFS-IA): there is a cost to retrieve files, lower price per storage

EBS vs EFS

• EBS volumes
  • Can be attached to only one instance at a time
  • Are locked at the AZ level
  • GP2: IO increases if the disk size increases
  • IO1: can increase IO independently
  • To migrate an EBS across AZ:
    • Take a snapshot
    • Restore the volume from the snapshot
  • Root EBS volumes get terminated by default in the EC2 instance is terminated (this feature can be disabled)
• EFS
  • Can be mounted to multiple instances across AZs via EFS mount targets
  • Available only for Linux instances
  • EFS has a higher price point than EBS
  • EFS is pay per second, we can leverage EFS-IA for cost saving