You are an AWS consultant in an IT company. Your development manager just assigned you a task to evaluate if the EBS volume types of the EC2 instances were properly configured in all regions. The major concern that you have found is that almost all EBS volumes are using the Provisioned IOPS SSD (io1) volume type which costs the company a lot. You plan to change the volume type from io1 to other types. However, for which scenarios should you still use the EBS volume type of io1?

Answer options:

A.A boot volume of a test server that is frequently used by the Quality Assurance team.
B.A Cassandra database that needs extremely low latency and high performance when being processed.
C.A data warehouse server that contains a huge amount of customer data. The data needs to be accessed and analyzed by a monitor process frequently.
D.Some large and legacy cold data that is stored to trace customers’ activities in the past. The database requires fewer scans per day.

Correct Answer:B
 
Refer to https://aws.amazon.com/ebs/features/ for the use cases of different EBS volume types:
Volume Type
EBS Provisioned IOPS SSD (io1)
EBS General Purpose SSD (gp2)*
Throughput Optimized HDD (st1)
Cold HDD (sc1)
Short Description
Highest performance SSD volume designed for latency-sensitive transactional workloads
General Purpose SSD volume that balances price performance for a wide variety of transactional workloads
Low-cost HDD volume designed for frequently accessed, throughput intensive workloads
Lowest cost HDD volume designed for less frequently accessed workloads
Use Cases
I/O-intensive NoSQL and relational databases
Boot volumes, low-latency interactive apps, dev & test
Big data, data warehouses, log processing
Colder data requiring fewer scans per day
Option A is incorrect: Because according to the above introductions, this should be a gp2 for a boot volume.
Option B is CORRECT: Because this is ideal for io1 as it needs the highest performance and lowest latency.
Option C is incorrect: Because this should be an st1, it could lower the cost and meet the performance need.
Option D is incorrect: Because sc1 is suitable for this as it is not frequently used. Moreover, because it contains a large amount of data, using io1 is not cost-efficient.