Purchasing Options

Question 1

On-Demand

Answer 1

• Pay for what you use
• high cost
• no upfront payment
• no long term commitment
• Recommended for: short term, uninterrupted workloads where you can’t predict how the app will behave

Question 2

Reserved

Answer 2

• 75% discount compared to on demand
• Choose 1 year (discount) or 3 years (more discount)
• Purchasing options
  
  • no upfront
  • partial upfront (discount)
  • all upfront (bigger discount)
• Reserve a specific instance type
• Recommend: steady-state usage applications (like database)

Question 3

Convertible reserved instance

Answer 3

• Change the EC2 instance type over time

- up to 54% discount

Question 4

Scheduled reserved instance

Answer 4

• launch within time window you reserve
• use when require app to run for a fraction of a day/week/month periodically
• commitment: 1-3 years

Question 5

Spot Instances

Answer 5

• up to 90% discount
• can lose them at any time if the price you’re willing to pay for them is less than the current spot price
• recommended: for workloads that are resilient to failure
  
  • batch jobs
  • data analysis
  • image processing
  • distributed workloads
  • workloads with flexible start and end time
• Not suitable for database or critical jobs

Question 6

Dedicated Instances

Answer 6

• instances running on hardware that’s dedicated to you
• may share hardware with other instances in the same account
• no control over instance placement (can move after start/stop of instance)
• soft version of dedicated host

Question 7

Dedicated hosts

Answer 7

• 3 year period reservation / most expensive
• Renting an entire server in a data center
• For companies that have strong regulatory or compliance needs
• Allow you to use your existing server-bound software licences

Question 8

Spot Fleets

Answer 8

Automatically request spot instances with the lowest price

• set of spot instances + (optional) on-demand instances
• try to meet the target capacity with the price constraints
• define multiple launch pools - instance type, OS, availability zone
• fleet will choose the best launch pool for you
• when budget is reached, it stops launching instances

Question 9

Strategies to allocate Spot Instances

Answer 9

• lowest price
  
  • cost optimisation, short workload
• diversified
  
  • distributed across all pools
  • great for availability, long workloads
• capacityOptimised
  
  • launch instances from pool with optimal capacity for the number of instances