Here is a very high level summary of what I learned about EC2 from their documentation.
- The virtual servers in EC2 environment are basically the running instances of AMI (Amazon Machine Image). AMI contains all the software, including OS and associated configuration settings, applications, libraries etc.
- There are already many existing AMI (free as well as paid). Also, new AMI can be created from scratch or based on an existing AMI. However, new AMI has to be saved on Amazon S3 (Simple Storage Service) and there is a charge for this storage.
- There are different types of instances based on CPU, Memory, Storage and I/O requirements and accordingly Amazon has different pricing for each type of instance.
- AMI instances are not persistent. You lose all the changes when you shutdown your OS or terminate the AMI instance.
- For all the online data that requires persistence (for example, a DB2 database), they have a different solution. It’s called Elastic Block Store (EBS). EBS is storage volume that can be attached to the host (running instances of AMI) and it can either be used as raw device or a file system can be created on it.
- Snapshots of EBS can be created on the Amazon S3 (Simple Storage Service). EBS snapshot can be used to launch new EBS volumes using the previous snapshot as the starting point of those new volumes.
- Static IP addresses can also be assigned to instances. They are called Elastic IP address.
- We can access the servers hosted in EC2 environment using SSH client or Remote Desktop.