AWS EC2 Terminology

- Virtual Server = Instances (Powered On or Off)
- Amazon Machine Image (AMI) = Machine Disk Template to create machine in the cloud
- Ephemeral (A-phem-ral) Storage = Instance Hard Disk (Temporary), when you power down the machine its gone (deleted). Mostly used for templates.
- Elastic Block Store (EBS) = Instance Hard Disk saved. They are slower than the ephemeral storage. They stay around after you power off. EBS drives are replicated to another system. Ensure you have a backup.
- Elastic Compute Unit (ECU) = Measure of EC2 Processor. More info below:

Understanding Processing Power Ratings:
- Everything in AWS is virtual, but they really are physical items.
- To provide consistent performance, AWS created the EC2 compute unit (ECU).
    - 1.0 – 1.2 GHz 2007 Xeon processor, that’s the measure of speed.
    - Combine that with the number of cores

Measuring Instance Types: Instance types always include a mix of memory, processing power, storage and I/O performance. Best practice would be to start small, benchmark and scale up if necessary.

Instance Family: Micro, Standard, High-memory, High CPU, cluster compute and Cluster GPU.

Understanding I/O Ratings:
- Memory and CPU resources are quantifiable and dedicated
- I/O ratings measure shared resources (Network / Disk)
- Equal shares given to the instances (Burstable)
- I/O levels: Low, Moderate, High and Very High – SSD Disks.


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