Amazon Elastic Compute Cloud

Compute is the amount of resources (Memory, CPU, Network Performance, Storage) required to fulfill a workload. EC2 is Amazon's offering for compute. There are many flavors that offer different combinations of resources optimized for different kinds of tasks.

• Amazon Machine Images (AMI) are the initial state for EC2 instances (snapshot of computer state)
• security groups act as a firewall for inbound (and outbound) network traffic
• storage is ephemeral unless an Elastic Block Storage Volume (EBS) is mounted
• three instance types: on-demand, reserved and spot
• spot instances are cheapest and are purchased based on highest bidding customers, which means machines can be shut down at any time based on market demand
• placement groups are logical groups of instances that allow for co-location within availability zones to reduce network latency
• Elastic Block Store provides persistent block storage, which is useful for durability where instance storage isn't sufficient
  • magnetic volumes are cheapest
  • general-purpose SSD which accumulates I/O operations per second (IOPS) credits when inactive and otherwise are slightly rate limited for cost efficiency
  • provisioned IOPS SSDs allow you to specify I/O requirements and pay for what you need
  • EBS contends for some of the network throughput for an instance, and I imagine that I/O operations have significantly higher latency than on instance storage while costing more
• Amazon EBS-optimized instances ensure additional dedicated network capacity for the EBS I/O

Scripting

user data is a configurable parameter that allows execution of scripts or configuration tasks

• two types are shell scripts and cloud-init directives
• cloud-init is a tool across many linux distributions for automating config and setup alongside AMIs or as a part of AMIs

Block Device Mapping

Each system has an associated root device volume (EBS or instance store). Block device mapping allows additional EBS or instances store volumes to be attached to the system on launch.

• a block device is a OS-level concept