EC2 Purchasing Options

  • On-Demand
  • Reversed
  • Spot
  • Dedicated Hosts
Metrics On-Demand Reserved Spot
Discount 0% 40%-60% 50%-90%
Description There’s no commitment from you. You pay the most with this option. 1-year or 3-year commitment from you. You save money from that commitment Ridiculously inexpensive because there’s no commitment from the AWS side.
Use Case Small or experimental project that do not anticipate the need of config to be used or used in a short time such as:
  • Software testing
  • Build a system that runs seasonally
  • The system needs to be deployed quickly but can stop at any time (actively)
 A server for long-term purpose
  • Limited cost
  • Applications can stop at any time without affecting the system: Like jobs that need to be processed once requiring high processing speed, CI/CD, …

EC2 Spot

EC2 Spot vs On-Demand

Metrics Spot Instances On-Demand Instances
Launch time Launches instantly if the Spot Request is active and capacity is available. Launches instantly when you make a manual launch request and capacity is available.
Available capacity Delivers launch requests until capacity becomes available. Sends an insufficient capacity error when the request is made and no capacity is available.
Hourly price Varies depending on supply and demand. Remains the same.
Rebalance recommendation Sends a warning signal when the instance is at high risk for interruption. Continues to run until you terminate or hibernate the instance.
Instance interruption Interruptible by AWS EC2 when capacity is no longer available, the prices exceed your budgeted max rate, or the demand for Spot instances increases. Remains uninterrupted until you terminate or hibernate the instance.

Spot Fleets

Spot Fleets = set of Spot Instances + (optional) On-Demand Instances

The Spot Fleet will try to meet the target capacity with price constraints

  • Define possible launch pools: instance type, OS, AZ
  • Can have multiple launch pools, so that the fleet can choose the best and most appropriate launch pool
  • When the spot fleet either reaches the budget or the capacity, then it will stops launching instances.

Strategies to allocate Spot Instances:

  • lowestPrice: from the pool with the lowest price (cost optimization, short workload)
  • deversified: distributed across all pools (great for availability, long workloads)
  • capacityOptimized: pool with the optimal capacity for the number of instances

Spot Fleets allow us to automatically request Spot Instances with the lowest price