Exam AWS Certified SysOps Administrator - Associate topic 1 question 83 discussion

It is D: ApproximateNumberOfMessagesVisible Metric: This metric indicates the number of messages waiting to be processed in the Amazon SQS queue.Number of InService Instances:The scaling decision should consider the number of currently available EC2 instances in the Auto Scaling group to handle the load efficiently. Custom Metric:By creating a custom metric that divides the ApproximateNumberOfMessagesVisible by the number of running (InService) instances, you can calculate the per-instance workload.Posting the Metric to CloudWatch:Once the application posts this custom metric to Amazon CloudWatch, you can create an Auto Scaling policy that uses it to scale the number of instances dynamically.\ B: ApproximateNumberOfMessagesDelayed refers to messages that were delayed because of SQS configurations like delay queues or retries. It doesn’t reflect the immediate workload waiting to be processed.

The answer is D: This approach involves custom monitoring of queue depth and instance count, allowing dynamic scaling based on workload demands. By combining both metrics, you can achieve responsiveness while considering varying processing times.

ApproximateNumberOfMessagesDelayed - The number of messages in the queue that are delayed and not available for reading immediately. This can happen when the queue is configured as a delay queue or when a message has been sent with a delay parameter. In our scenario the messages are not delayed in the queue - just not been picked up yet.

ApproximateNumberOfMessagesDelayed is a built in metric not a custom metric Answer is B

ApproximateNumberOfMessagesDelayed - The number of messages in the queue that are delayed and not available for reading immediately. This can happen when the queue is configured as a delay queue or when a message has been sent with a delay parameter. In our scenario the messages are not delayed in the queue - just not been picked up yet. Hence I vote for "D"

Looks like the answer is in this link: (D) ApproximateNumberOfMessagesDelayed: The number of messages in the queue that are delayed and not available for reading immediately. This can happen when the queue is configured as a delay queue or when a message has been sent with a delay parameter. Which means not that they are delayed because of the insufficient available capacity to process but "delayed" is more of a feature rather than a result of something. ApproximateNumberOfMessagesVisible: The number of messages to be processed.

Modifying an application is almost always a no-no in AWS exams. so I will go with B.

I thought B, but it looks D. numberofDelay seems just delay setting msg, not queued msg : B. ApproximateNumberOfMessagesDelayed – Returns the approximate number of messages in the queue that are delayed and not available for reading immediately. This can happen when the queue is configured as a delay queue or when a message has been sent with a delay parameter. D. ApproximateNumberOfMessagesNotVisible – Returns the approximate number of messages that are in flight. Messages are considered to be in flight if they have been sent to a client but have not yet been deleted or have not yet reached the end of their visibility window.

if ApproximateNumberOfMessagesDelayed is increasing, wouldnt it be a good way to make the ASG scaling? Also providing the scalability accordingly to the problem its facing? And "modifying the application to calculate.." doesnt also sound for something to the devs, not for the SysOps Administrator? I'm going for B.

When there are delays in processing files due to a high volume of messages in the queue, adding more instances using Auto Scaling can help to reduce the processing time. The ApproximateNumberOfMessagesVisible metric is a good indicator of the workload on the EC2 instances. By creating an Auto Scaling policy based on this metric, the number of instances can be scaled up or down depending on the number of messages in the queue.

C. D: There is no "ApproximateNumberOfMessagesVisible" parameter. It should be ApproximateNumberOfMessagesNotVisible

AWS offers even an example for this - https://docs.aws.amazon.com/autoscaling/ec2/userguide/ec2-auto-scaling-target-tracking-metric-math.html#metric-math-sqs-queue-backlog

I'm agree with D

The issue here is that the app is taking too long to process the files. This means that the messages are in the SQS queue, just they're not being processed fast enough. It can't be B as "ApproximateNumberOfMessagesDelayed – Returns the approximate number of messages in the queue that are delayed and not available for reading immediately" (https://docs.aws.amazon.com/AWSSimpleQueueService/latest/APIReference/API_GetQueueAttributes.html). This would mean that the messages are not available, which isn't the case in this question The link posted by zolthar_z clearly explains why it's D. The app takes a variable amount of time to process each message, hence the app should calculate the Backlog per instance

The answer is D: https://docs.aws.amazon.com/autoscaling/ec2/userguide/as-using-sqs-queue.html

It's D

Ans: B