A financial company recently added more features to its mobile app. The new features required the company to create a new topic in an existing Amazon…

The scenario describes a disk space issue (RootDiskUsed alarm) that occurred after adding a new topic, which implies an increase in data volume. The most direct and standard solution for insufficient storage capacity in Amazon MSK is to increase the size of the EBS storage volumes attached to the brokers. Option A proposes exactly this, along with the best practice of enabling automatic storage expansion. This feature uses CloudWatch alarms to monitor disk usage and proactively increases storage, preventing future alarms and potential service disruptions caused by full disks. This directly addresses the root cause—increased data storage requirements from the new topic.

1. Amazon MSK Developer Guide

Troubleshooting

"Broker out of disk space": This official guide states

"This issue can happen when the traffic to your cluster is higher than what the cluster can handle

or when the storage on the cluster is not enough to hold your messages... To resolve this issue

first try to increase the storage of your cluster." This directly supports increasing broker storage.

2. Amazon MSK Developer Guide

"Amazon MSK storage autoscaling": This document describes the feature for automatically expanding storage. It says

"Amazon MSK storage autoscaling uses Amazon CloudWatch alarms to monitor your brokers' storage utilization. When storage utilization reaches a certain threshold

storage autoscaling automatically initiates a storage increase for your cluster." This validates the second part of option A.

3. Amazon MSK Developer Guide

"Updating broker type and storage": This page clarifies the process for modifying a cluster

distinguishing between updating the broker type (for compute) and updating storage. It details the UpdateBrokerStorage operation

which is the action described in option A.

4. Amazon MSK Developer Guide

"Monitoring an Amazon MSK cluster": This section details the available CloudWatch metrics

including RootDiskUsed and KafkaDataLogsDiskUsed. While the question names RootDiskUsed

the context of adding a new topic points to a data volume issue

for which increasing the data log storage is the correct remedy.