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Exam AWS Certified Solutions Architect - Professional topic 1 question 1003 discussion

Exam question from Amazon's AWS Certified Solutions Architect - Professional

Question #: 1003
Topic #: 1

[All AWS Certified Solutions Architect - Professional Questions]

A company uses an on-premises data analytics platform. The system is highly available in a fully redundant configuration across 12 servers in the company's data center.

The system runs scheduled jobs, both hourly and daily, in addition to one-time requests from users. Scheduled jobs can take between 20 minutes and 2 hours to finish running and have tight SLAs. The scheduled jobs account for 65% of the system usage. User jobs typically finish running in less than 5 minutes and have no SLA. The user jobs account for 35% of system usage. During system failures, scheduled jobs must continue to meet SLAs. However, user jobs can be delayed.

A solutions architect needs to move the system to Amazon EC2 instances and adopt a consumption-based model to reduce costs with no long-term commitments. The solution must maintain high availability and must not affect the SLAs.

Which solution will meet these requirements MOST cost-effectively?

A. Split the 12 instances across two Availability Zones in the chosen AWS Region. Run two instances in each Availability Zone as On-Demand Instances with Capacity Reservations. Run four instances in each Availability Zone as Spot Instances.
B. Split the 12 instances across three Availability Zones in the chosen AWS Region. In one of the Availability Zones, run all four instances as On-Demand Instances with Capacity Reservations. Run the remaining instances as Spot Instances.
C. Split the 12 instances across three Availability Zones in the chosen AWS Region. Run two instances in each Availability Zone as On-Demand Instances with a Savings Plan. Run two instances in each Availability Zone as Spot Instances.
D. Split the 12 instances across three Availability Zones in the chosen AWS Region. Run three instances in each Availability Zone as On-Demand Instances with Capacity Reservations. Run one instance in each Availability Zone as a Spot Instance.

Show Suggested Answer

Suggested Answer: D 🗳️

by Spavanko at Nov. 29, 2022, 7:10 p.m.

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daveshell

7 months, 2 weeks ago

Apart from whoever answered D, for others, please note that the other two main terms to note(outside of the strict SLA for the scheduled jobs) are, "consumption-based model" and "no long-term commitments". They both point to "on-demand" option and which is C & D. While C can do the job, there is a long-term commitment in using the savings plan.

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backbencher2022

10 months, 2 weeks ago

Selected Answer: C

C is correct

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Bengi

1 year, 11 months ago

C is correct. Assuming a fully redundant system requires 12 servers, so would require 6 servers to handle normal traffic. 6 x 0.65 = 3.9 Taking into account scheduled jobs and a 65% utilization rate, at least 4 machines are needed to meet high availability requirements under normal load conditions, with 2 spot instances per availability zone (for a total of 6 machines) to save costs.

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Bengi

1 year, 11 months ago

A: AZ1 (2 on-demand + 4 spot) / AZ2 (2 on-demand + 4 spot) - does not meet high availability requirements, as if one availability zone goes down, the other availability zone may not be able to obtain spot instances, resulting in the inability to meet the SLA for scheduled jobs (at least 4 instances). B: AZ1 (4 on-demand) / AZ2 (4 spot) / AZ3 (4 spot) - does not meet high availability requirements, as if AZ1 goes down, AZ2 or AZ3 may not be able to obtain spot instances, resulting in the inability to meet the SLA for scheduled jobs (at least 4 instances). C: AZ1 (2 on-demand + 2 spot) / AZ2 (2 on-demand + 2 spot) / AZ3 (2 on-demand + 2 spot) - meets the requirements, as if any availability zone goes down, there will always be 4 on-demand instances available to ensure the SLA is met. D: AZ1 (1 on-demand + 1 spot) / AZ2 (3 on-demand + 1 spot) / AZ3 (3 on-demand + 1 spot) - results in wasted resources.

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Bengi

1 year, 10 months ago

keyword user jobs can be delayed. user jobs no SLA. So only need to fulfil the schedule jobs.

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ggrodskiy

1 year, 11 months ago

Correct D.

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ggrodskiy

1 year, 11 months ago

Correct C.

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dev112233xx

2 years, 1 month ago

Selected Answer: D

D is correct imo.. 65% of 12 Instances = 7.8, so we need at least 8 instances that will not run as spot The only answer that gives this amount of instances is D - 9 Also, Capacity reservation has a higher SLA because they always will be available

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zejou1

2 years, 3 months ago

Selected Answer: D

It is D because of "model to reduce costs with no long-term commitments". That is a "requirement" so even though C would save the most money, D provides availability, meets demand via On-Demand Capacity Reservations, spot instances, and you could (if you like it) change it to Savings plan but https://docs.aws.amazon.com/savingsplans/latest/userguide/what-is-savings-plans.html Once you do On-Demand w/ Savings plan you are committing to 1-3 year term. Don't rely on just ChatGPT

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IvanHuang

2 years, 3 months ago

Selected Answer: C

ChatGPT:Option C: Split 12 instances across three Availability Zones, using the Savings Plan to run two instances in each Availability Zone as On-Demand Instances. Run two instances in each Availability Zone as Spot Instances. This solution takes full advantage of Capacity Reservation, On-Demand, and Spot Instances. Use the Savings Plan to reduce costs while On-Demand and Spot Instances provide elasticity and high availability. Therefore, this option is the most cost-effective option.

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Vash2303

2 years, 5 months ago

Selected Answer: B

B 6 active instance in a setup of 12 instance with full redundancy. 65% of 6 (=3.9) is needed to meed SLA running at 100% utilisation. hence you need at least 4 instance at a time.

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ignorica

2 years, 4 months ago

If you have 4 instances On-Demand in AZ-1 => SLA is good. AZ-1 dies -> how would SLA still be maintained if the instances are Spot Instances in the other AZs ?

upvoted 2 times

ignorica

2 years, 4 months ago

why not C ? if an AZ dies, there are always other 2 x AZs left with the proper capacity (3.9 as calculated before) With a Savings Plan the cost of running 6 On-Demand will also go a bit down.

upvoted 4 times

Amac1979

2 years, 4 months ago

I would go with C. Savings plan offer 60-70% savings compare to on-demand pricing. Capacity reservations gives you availability of resources not the cost saves.

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