A startup IT company just migrated its most important web application from on-premises to AWS. There is a strong need to design a disaster recovery system in AWS as soon as possible otherwise any outage may result in a huge impact on the company’s reputation and cash flow. However, the company is running out of budget and has to control any operation cost. Which AWS tools can help the company to control the cost while designing a disaster recovery system? (Select TWO.)

Answer options:

A.Create more spot instances in the hot standby system. 
B.Use a suitable Auto Scaling Group to control the number of running instances.
C.Use a Trusted Advisor to monitor the EC2 instances that have a low utilization rate in the standby system. Terminate those instances to save costs.
D.Use an S3 lifecycle policy to move all stored data in S3 to Glacier after one day to lower down the cost.
E.Use Amazon Data Lifecycle Manager to delete old EBS snapshots.

Correct Answer – B, E
While considering the services to lower down the cost, it is also necessary to make sure that the system can recover as normal and meet the given RPO and RTO.
Option A is incorrect: Because spot instances are unsuitable in the production environment no matter it is in a live system or backup system.
Option B is CORRECT: Because Auto Scaling Group helps on adjusting the number of running instances to save cost.
Option C is incorrect: Because the EC2 instances in the standby system should not be terminated even if their utilization rate is low. For a hot standby system, the instances in the standby should always run.
Option D is incorrect: Because it is unsafe to move all data to Glacier as it may cause issues if the backup is needed under a short RTO.
Option E is CORRECT: Because Amazon Data Lifecycle Manager helps to manage EBS snapshots efficiently. Old snapshots can be deleted to save costs.
Refer Section "Automating the Amazon EBS snapshot lifecycle" on page 1055 in the link: https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ec2-ug.pdf#AmazonEBS