Exam AWS Certified Solutions Architect - Associate SAA-C02 topic 1 question 124 discussion

Ans: A. The use cases mentioned has exact match with this. Even spot fleet you can set types of instances and max number of instances. So, If instance terminated then also Hadoop job will be continued with newly created instance. What is a Spot fleet? A Spot Fleet allows you to automatically request and manage multiple Spot instances that provide the lowest price per unit of capacity for your cluster or application, like a batch processing job, a Hadoop workflow, or an HPC grid computing job. You can include the instance types that your application can use. You define a target capacity based on your application needs (in units including instances, vCPUs, memory, storage, or network throughput) and update the target capacity after the fleet is launched. Spot fleets enable you to launch and maintain the target capacity, and to automatically request resources to replace any that are disrupted or manually terminated.

Spot Fleet is the answer This is a typical use case for Spot Fleet. Scheduled Reserved Instance would have been a closer match than Reserved Instance. RI are very costly. https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/spot-fleet.html This works well for workloads such as big data and analytics, image and media rendering, machine learning, and high performance computing that may have a higher cost of interruption associated with restarting work and checkpointing. By offering the possibility of fewer interruptions, the capacityOptimized strategy can lower the overall cost of your workload.

workloads run each night, and it is critical they finish by the start of business the following day ,,,that mean all night > Reserved Instance for me is the best

Spot Fleet : spot instances & on-demand

A Spot Fleet is a set of Spot Instances and optionally On-Demand Instances that is launched based on criteria that you specify. The Spot Fleet selects the Spot capacity pools that meet your needs and launches Spot Instances to meet the target capacity for the fleet. By default, Spot Fleets are set to maintain target capacity by launching replacement instances after Spot Instances in the fleet are terminated. You can submit a Spot Fleet as a one-time request, which does not persist after the instances have been terminated. You can include On-Demand Instance requests in a Spot Fleet request. Spot fleet is just spot instance with the default to change it to on demand if the instance terminated.

"it is vital that they be completed before the start of business the following day" There is no guarantee the spot instances will be available.

I feel like it is C, as you cannot guarantee the spot instances will be available and it will be completed. "it is vital that they be completed before the start of business the following day"

A https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/spot-fleet.html

On demand is out ..to costly. Reserved is out again costly to reserve 24/7 for a year.. Spot instance also out since availability is not guaranteed

I'd go with C - Reserved Instances - "it is vital that they be completed before the start of business the following day". You cannot guarantee that the job will be finished with spot instances. Adding on-demand instances to the fleet to ensure that the job is finished on time may make it more expensive than reserved instances (would depend on the % of spot vs on-demad).

Ans: C Spot instances can not be used in this scenario. Because it is vital to be completed before the following day starts.

Has to be A , since there is no mention of job can withstand failure

A: in spot fleet, you can : - Scheduled scaling – Increase or decrease the current capacity of the fleet based on the date and time https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/spot-fleet-automatic-scaling.html

I will go with C. Spot instances can be dropped and jobs has to completed by Morning.

A. Spot Fleet

Answer is A

Key word The MOST cost effective solution... https://blog.boltops.com/2018/07/13/on-demand-vs-reserved-vs-spot-aws-ec2-pricing-comparison