A recent increase of users of an application hosted on an EC2 instance has caused the instance’s OS to run out of CPU resources and crash. The crash caused several users’ unsaved data to be lost, and your supervisor wants to know how this problem can be avoided in the future. Which of the following would you NOT recommend?

Answer options:

A.Redesign the application so that users’ unsaved data is periodically written to disk.
B.Take frequent snapshots of the EBS volume during business hours to ensure users’ data is backed up.
C.Snapshot the EBS volume and re-deploy the application server as a larger instance type.
D.Use Auto Scaling to deploy additional application server instances when the load is high.

Answer – B
Option A is incorrect because this option would ensure that the user`s unsaved data gets preserved just in case the instance crashes.
Option B is CORRECT because taking frequent snapshots of the EBS volume during business hours may cause data loss (losing the data that is not yet written to the volume backed up via snapshot). AWS is strongly recommended to either detach the volume or freeze all writes before taking the snapshot to prevent data loss. Hence, this option is certainly not recommended.
Option C is incorrect because using a larger instance type can mitigate the problem of the instance running out of CPU.
Option D is incorrect because Auto Scaling will ensure that that at least one (or minimum number of) instance(s) would be running to ensure that the application is always up and running.
For more information on EBS snapshots, please refer to the below URLs-
http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/EBSSnapshots.html
https://forums.aws.amazon.com/thread.jspa?threadID=92160