You currently have 9 EC2 instances running in a Placement Group.
All these 9 instances were initially launched at the same time and seem to be performing as expected.
You decide that you need to add 2 new instances of different instance types to the group.
However, when you attempt to do this, you receive a 'capacity error'
Which of the following actions will most likely fix this problem? Choose the correct answer from the options below.
Click on the arrows to vote for the correct answer
A. B. C. D.Answer - B.
Refer link.
https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/placement-groups.html#concepts-placement-groups"If you try to add more instances to the placement group later, or if you try to launch more than one instance type in the placement group, you increase your chances of getting an insufficient capacity error."
This is also given in the AWS DocumentationInsufficient Instance Capacity.
Description.
You get the InsufficientInstanceCapacity error when you try to launch a new instance or restart a stopped instance.
Cause.
If you get an InsufficientInstanceCapacity error when you try to launch an instance or restart a stopped instance, AWS does not currently have enough available On-Demand capacity to service your request.
Solution.
To resolve the issue, try the following:
Wait a few minutes and then submit your request again; capacity can shift frequently.
Submit a new request with a reduced number of instances.
For example, if you're making a single request to launch 15 instances, try making 3 requests for 5 instances or 15 requests for 1 instance instead.
If you're launching an instance, submit a new request without specifying an Availability Zone.
If you're launching an instance, submit a new request using a different instance type (which you can resize at a later stage)
For more information, see Changing the Instance Type.
If you are launching instances into a cluster placement group, you can get an insufficient capacity error.
For more information, see Placement Group Rules and Limitations.
Try purchasing Reserved Instances, which are long-term capacity reservation.
For more information, see Amazon EC2 Reserved Instances.
Options A, C and D are all invalid because none of these options will help resolve the error.
For more information on this error, just browse to the below URL:
http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/instance-capacity.htmlThe correct answer is C: Request a capacity increase from AWS as you are initially limited to 10 instances per Placement Group.
A Placement Group is a logical grouping of instances within a single Availability Zone. When instances are launched in a Placement Group, AWS attempts to place them physically close to each other in order to reduce network latency and improve performance.
By default, the maximum number of instances that can be launched in a Placement Group is 10. This is a hard limit that cannot be increased by the user. Therefore, if you attempt to add new instances to a Placement Group that already contains 9 instances, you will receive a "capacity error" as stated in the question.
The correct solution to this problem is to request a capacity increase from AWS. This can be done by contacting AWS Support and providing the necessary details, such as the region and the number of instances that you require. Once the capacity increase is approved, you should be able to launch the additional instances in the Placement Group.
Option A, creating a new Placement Group, may not be desirable as it would require moving the existing instances to the new group, which could result in downtime and network latency issues.
Option B, replacing instances of the same type, would not resolve the capacity issue as the maximum number of instances per Placement Group is still 10.
Option D, making sure that all instances are the same size, is not relevant to the capacity issue and would not resolve the problem.