Which AWS Service Monitors EC2 Disk Write Spikes?
Which AWS service or feature can be used to monitor for potential disk write spikes on a system that is running on Amazon EC2?
Community Insight
The question tests the distinction between monitoring/metrics (CloudWatch) and auditing, service-health or advisory tooling — the trap is picking CloudTrail because it also records EC2-related activity.
Amazon CloudWatch is the AWS service used to monitor EC2 instance metrics, including disk write activity, and to raise alarms when write volume spikes. This page confirms D as the answer and explains why CloudTrail, AWS Health Dashboard and Trusted Advisor cannot perform metric-level disk monitoring.
Choosing AWS CloudTrail (A) because it 'records what happens on EC2'; CloudTrail logs API activity and management events, not disk write throughput or storage performance metrics.
Community Discussion (3 comments)
Comments & Corrections
No comments yet — spotted an error or have a note? Share it below.
Expert Analysis
Why the Answer Is Correct
Amazon CloudWatch is AWS's monitoring and observability service: it ingests time-series metrics for EC2 instances and lets you graph them, set thresholds and trigger alarms or Auto Scaling actions. Disk write activity is exactly that kind of performance telemetry, so a spike can be detected with a CloudWatch alarm on metrics such as disk write operations or write bytes. Because CloudWatch is the native metrics store for AWS resources, it is the only option here that provides real-time, quantitative disk-level monitoring. The community agreed: as Yomijohnson wrote, "It provides metrics, including those related to disk performance", and its_tima described CloudWatch as the service for "monitoring and observing resources in real-time".Why the Other Options Are Wrong
AWS CloudTrail (A) is an audit and governance service — it records API calls and account activity (who did what, when, from where), not CPU, disk or network performance counters, so it cannot detect a write spike. AWS Health Dashboard (B) reports service health events, scheduled changes and issues affecting your account or specific AWS services; it is about availability notifications, not EC2 disk throughput. AWS Trusted Advisor (C) inspects your account against best-practice checks (cost, security, fault tolerance, service quotas) and offers recommendations, but it does not stream per-instance disk metrics or fire real-time alarms on write volume. Each of these watches a different layer of the stack, which is why only CloudWatch answers a performance-monitoring question.Community Comment Notes
All three comments select D, and the reasoning is consistent: monitoring resource metrics in near real time. Yomijohnson emphasises that alarms can be configured "to notify you of potential disk write spikes or other performance issues", which is precisely the use case in the question. its_tima frames CloudWatch as the tool that gives "data and actionable insights" for application monitoring and resource optimization. d00b229 simply records D without elaboration. One nuance worth remembering for the exam: instance-level disk metrics for EC2 come from the CloudWatch agent, while basic metrics like CPUUtilization are available by default.Official Reference
Exam Strategy
When a question asks about monitoring, metrics, thresholds, alarms or performance trends for an AWS resource, CloudWatch is almost always the answer — reserve CloudTrail for auditing API activity and Trusted Advisor for best-practice checks. Scan the wording for signals like "spike", "utilization" or "real-time", which point to metrics rather than logs or health events.
Frequently Asked Questions
Why can't AWS CloudTrail detect an EC2 disk write spike?
CloudTrail records API calls and account activity for auditing, not performance counters like disk write operations, so it has no metric to alarm on.
Do EC2 disk write metrics appear in CloudWatch by default?
No. Basic metrics such as CPUUtilization are automatic, but disk and memory metrics require the CloudWatch agent installed on the instance.
Related Analysis
Practice All CLF-C02 Questions
Access 120 questions with complete answers and detailed explanations.
View Full CLF-C02 Practice Test →