EFS, or Elastic File system is a powerful alternative to EBS. If an EBS is a network drive, then EFS is a NFS that can be accessed by multiple instances ACROSS DIFFERENT AZ utilizing NFS v4.1. It is only available with linux based AMI, not windows. It scales up along side your usage and you just pay for what you use. If you access certain files infrequently you can utilize EFS-IA, infrequent access, this charges a fee for when you need to access those files, but you pay much less to store them. You can even setup a lifecycle management feature to move files to the IA tier after n number of days . Using EFS across multiple AZ is excellent for production systems, but it may be best to stick to one AZ regarding development it will save a good amount. You can set performance mode as well to either general purpose, for applications that require low latency such as web servers or user facing applications, or if latency isn’t a concern and you want high I/O for data processing you can utilize max I/O.