A user has setup an EBS backed instance and a CloudWatch alarm when the CPU utilization is more than 65%.
The user has setup the alarm to watch it for 5 periods of 5 minutes each. The CPU utilization is 60% between 9
AM to 6 PM. The user has stopped the EC2 instance for 15 minutes between 11 AM to 11:15 AM. What will be
the status of the alarm at 11:30 AM?
A.
Alarm
B.
OK
C.
Insufficient Data
D.
Error
Explanation:
Amazon CloudWatch alarm watches a single metric over a time period the user specifies and performs one or
more actions based on the value of the metric relative to a given threshold over a number of time periods. The
state of the alarm will be OK for the whole day. When the user stops the instance for three periods the alarm
may not receive the data
Answer is B , it is not going to change if you stop EC2
I would go with C
http://docs.aws.amazon.com/AmazonCloudWatch/latest/monitoring/AlarmThatSendsEmail.html
Note
Some AWS resources do not send metric data to CloudWatch under certain conditions.
For example, Amazon EBS may not send metric data for an available volume that is not attached to an Amazon EC2 instance, because there is no metric activity to be monitored for that volume. If you have an alarm set for such a metric, you may notice its state change to Insufficient Data. This may simply be an indication that your resource is inactive, and may not necessarily mean that there is a problem.
b
The answer should be B.
A – threshold 65% not breached for 25min.
B – threshold is below 65% in the above cases even when the instance has been stopped.
C – only if we terminate the instance.
D – Exeptional
Update:
C- only when we terminate/stops the instance, if not receive data for 5 periods of 5min(25min).
It will be B – OK.
The reason being, 3 monitor periods have completed, after the 15 minute stoppage. During the 15 minute stoppage, there would have been Insufficient Data
Answer is B
“if some data points during the current window are missing, CloudWatch looks back extra periods to find other existing data points to use to assess whether the alarm should change state. CloudWatch does this to avoid going to INSUFFICIENT_DATA when possible. When CloudWatch does this, if the furthest back period that is now being considered is not breaching, the alarm state will not go to ALARM.”
http://docs.aws.amazon.com/AmazonCloudWatch/latest/monitoring/AlarmThatSendsEmail.html
It’s B, since the user stopped the EC2 instance for 15 minutes, and the alarm it’s set for 5 periods of 5 minutes which is 25 minutes.
CPUUtilization >= 65 for 25 minutes
B
B.
OK