AWS EC2 Instance Types

Types of EC2 Instance
The hardware of the host computer that is used to run the instance is determined by the EC2 Instance type.
Different EC2 instance types offer different compute and memory & storage capabilities. They are grouped into instance families based upon these capabilities
EC2 provides every instance with a predictable and consistent amount of CPU capacity regardless of its underlying hardware.
EC2 allocates resources from the host computer such as memory, CPU, and instance storage to a specific instance.
EC2 shares resources with the host computer, including the network and disk subsystem. Each instance on a host computer will get an equal share of the shared resources if it tries to use as many of each of these resources as possible. If a resource is not being used as efficiently as possible, an instance may consume more of that resource. Please refer to AWS documentation for further details.
EC2 Instance Types: Current GenerationEC2 Types Selection criteria
Some instances support only HVM virtualization while others support both PV and HVM virtualization types. AWS recommends that you use HVM to take advantage of the underlying hardware.
VPCs can host all EC2 instance types, but some are not available in EC2-classics. AWS recommends VPC for enhanced networking, multiple IP addresses and finer security control.
Some instances only support EBS volumes while others support both EBS volume and Instance store volumes. Solid-state drives (SSDs) are used by some instances to support instance store volumes. They provide very high random I/O performance.
Some EC2 instance types may be launched as EBS optimized instances with a dedicated resource for EBS I/O.
To optimize instances for High-Performance Computing, (HPC), certain EC2 Instance types may be launched in a placement group.
Some instances support Enhanced Networking. This allows for significantly higher packet per se (PPS), lower network jitter and lower latencies.
Some Instances allow EBS volumes to be encryptedEBS-Optimized
EBS-optimized instances use an optimized configuration stack and provide additional capacity for EBS I/O
EBS-optimized instances allow you to achieve consistent high performance for EBS volumes by eliminating contention among EBS I/O from the instance
EBS-optimized instances provide dedicated throughput between Amazon EC2 or EBS. There are options between 500 and 60,000 Megabits of data per second (Mbps), depending on the type of instance.
Attached to an EBS-optimized instance are General Purpose (SSD), volumes that are designed for general purpose (SSD), are designed to deliver within ten percent of their baseline performance and burst performance 99.9 % of the times in a given calendar year. Provisioned IOPS volumes (SSD), are designed to deliver a minimum of 10 percent of their provisioned performance 99.9 % of the time in any given calendar year.
EBS optimization can also be enabled for instances that are not EBS-optimized by defaultPlacement groups
Refer to my Blog Post @ EC2 Plament Groups
ComparisionT2 Instance Types EC2 Instances (General Purpose).
T2 instances are designed for moderate baseline performance, but can burst to significantly greater performance as needed
This is a great option for workloads that don’t use the full CPU frequently or consistently but sometimes need to burst.
T2 instances are well-suited for general-purpose workloads such as web servers and remote desktops.
Only HVM AMI can launch requirements
Only a VPC can be launched, not the EC2-Classic.
Only EBS-backed instances are eligible
They are available as On-Demand or Reserved instances, Dedicated instances (T3 only), or Spot instances. However, they do not allow spot instances
By default, you can run 20 (soft limit T2 instances) simultaneously
It is not possible to launch as a dedicated host
T2 Unlimited