Exam AWS Certified SysOps Administrator - Associate topic 1 question 75 discussion

The questions says: "must be able to change the instance TYPE within the SAME instance FAMILY". Note that the question says TYPE, and not SIZE. According to https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ri-modifying.html, You can "Change the instance SIZE within the same instance family and generation" and "For example, you can modify a Reserved Instance from t2.small to t2.large because they're both in the same T2 family and generation. But you can't modify a Reserved Instance from T2 to M2 or from T2 to T3, because in both these examples, the target instance family and generation are not the same as the original Reserved Instance." In the above example: General Purpose Family, TYPE T, Generation 2, SIZE small (T2.large) (https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/instance-types.html#AvailableInstanceTypes) Convert it to T2.large. This is same TYPE (T2), different SIZE (large). Hence, Standard would cover it. However, if I want to change T3.small, this would be a different TYPE (T3) within the same family (General Purpose). Hope this example helps claryifing.

"..must be able to change the instance type within the same instance family later in the year "

Answer ia A and ChatGPT agrees Solution: Convertible Reserved Instances Cost-Effectiveness: Reserved Instances (RIs) offer significant discounts (up to 72%) compared to On-Demand pricing when the instances run continuously. Flexibility: Convertible RIs allow you to change the instance type, size, or even the operating system within the same family, which matches the company's requirement to adjust instance types later based on traffic.Commitment Period: Reserved Instances require a 1-year or 3-year commitment, suitable for 24/7 workloads.

BC pooree awaam sirf A aur D hee main larr rahee hai yahan and still there's no final consensus on it! :(

By GTP4o Given the company's need to run applications continuously throughout the year with the ability to adapt instance types based on traffic, Convertible Reserved Instances provide the best balance of cost savings and flexibility. This purchasing option ensures the company can optimize costs while retaining the flexibility to adjust their infrastructure as usage patterns evolve.

Change Type within the Instance's Family - Standard RIs allow this and they are cheaper. You don't require convertible RIs! period.

Convertible Reserved Instances allow for updating the instance type

Depending on context AWS uses both terms TYPE and SIZE to point on instance NAME (eg t3.medium). That's why many people got confused. Here it is SIZE: https://aws.amazon.com/ec2/instance-types/ Here it is TYPE: https://docs.aws.amazon.com/ec2/latest/instancetypes/gp.html In context of RI it states the following: Instance type: For example, m4.large. This is composed of the instance family (for example, m4) and the instance size (for example, large). In question the keys are 'within the same instance family' and 'most cost-effective' Standard RI allows to change instance type within the same family (m4.large -> m4.xlarge) and it is cheaper then Convertible RI

ok, the final comment to solve the argument in here as mentioned previously, the main clause in the question is "The company must be able to change __the instance type within the same instance family later__" so let's define what instance family, type (and size) mean, shell we e.g. "t2.small" instance - instance family "t2" - instance size ".small" - instance type "t2.small" so if the question requires the ability to change "the instance type within the same instance family", it means persistence of "t2" part and changing anything that goes after.

A!!! C is not correct because: Standard Reserved Instance enables you to modify ... instance size within the same instance type

d Convertible Reserved Instances (up to 55%) Standard Reserved Instances (up to 75%)

D because the text say "able to change the instance type within the same instance family" (type mean size here) and even if it's possible to change instance size and type with Convertible Reserved Instances (up to 55%) Standard Reserved Instances (up to 75%) is more cheaper than Convertible Reserved Instances

I will say A because there is a need to change instance type within instance family. With D you wouldn't be able to change instance generation and it's part of instance type.

A. Convertible Reserved Instances

https://docs.aws.amazon.com/whitepapers/latest/cost-optimization-reservation-models/standard-vs.-convertible-offering-classes.html instance type contains family reserved are cheaper Convertible Reserved Instances are useful when: Purchasing Reserved Instances in the payer account instead of a subaccount. You can more easily modify Convertible Reserved Instances to meet changing needs across your organization. Workloads are likely to change. In this case, a Convertible Reserved Instance enables you to adapt as needs evolve while still obtaining discounts and capacity reservations. You want to hedge against possible future price drops. You can’t or don’t want to ask teams to do capacity planning or forecasting. You expect compute usage to remain at the committed amount over the commitment period.

Standard Reserved Instances: These offer up to 75% off On-Demand pricing and are best for steady-state usage. The downside is the lack of flexibility in changing instance types, sizes, or families, which doesn't align with your requirement to adjust instance types based on traffic

D Standard RI is more cost effective than Convertible. BOTH allow change the instance size within the same instance family and generation.