AWS Storage: EBS, EFS, S3

Here are some of the main storage options in AWS: 

• EBS (Elastic Block Store)
• EFS (Elastic File System)
• S3 (Simple Storage Service)

I created the following diagram to help visualize how these work:

Instance Store: An EC2 Instance has local store, similar to a physical or virtual machine. 

For a Linux-based EC2 instance (such as Amazon Linux 2), there will be the typical / (root) directory, and standard Linux directories such as /bin, /etc, /opt, /tmp

For a Windows-based EC2 Instance, there is the typical C:\ directory. 

The problem with Instance Store is that it is not persistent or durable.  If the EC2 Instance is terminated, the data that was stored in /opt is gone. 

I/O is fast because there is no network latency between the EC2 Instance and its Instance Store.

EBS: Persistent, but is attached to a single EC2 Instance.  I think of it like plugging in an additional hard drive.  You can't connect it to multiple EC2 Instances because File Systems such as EXT4, NTFS don't handle that.  I/O is fast because there is no network latency between the EC2 Instance and EBS. 

EFS: Persistent, can be shared by multiple EC2 Instances and On-Prem Servers.  I think of this like a mounted drive on a NAS.

S3: Object-based.  Objects are placed into/retrieved from buckets using HTTPS.  This is going to be much less performant than other storage mechanisms, but would be the most globally-accessible.