I/O performance diagnostics: In operating system/device performance monitoring, what is “seeks analysis” typically used to diagnose?

Introduction / Context:
Rotating-disk storage (HDD) performance is heavily influenced by seek operations—the movement of the read/write head between tracks. Excessive seeking increases service time and can cause the device to be saturated (“device busy”). Seeks analysis focuses on this component of I/O latency.

Given Data / Assumptions:

• Traditional DASD/HDDs incur seek time, rotational latency, and transfer time.
• High seek rates indicate non-sequential access patterns or contention.
• Control-unit busy refers to controller saturation, a different bottleneck.

Concept / Approach:

Monitoring tools break down I/O waiting into components. Seeks analysis correlates workloads with head movement metrics to highlight random access patterns, poor locality, or queue contention. When seeks dominate, the device itself is frequently busy moving heads rather than transferring data, pointing to a device busy problem.

Step-by-Step Reasoning:

Verification / Alternative check:

Storage performance reports (e.g., iostat-like tools, vendor utilities) show seek/queue depth metrics; sustained high values correlate with device busy rather than control-unit bottlenecks.

Why Other Options Are Wrong:

• Paging problems: Though paging can generate I/O, seeks analysis targets disk head motion, not specifically virtual memory policy.
• Control-unit busy: That is a controller-level bottleneck; seeks analysis is about the device’s mechanical activity.
• Only real-time displays: Analysis can be historical, not just real-time.
• None of the above: Incorrect because device busy analysis fits.

Common Pitfalls:

Assuming all I/O latency equals seek time; ignoring SSDs where seek time is negligible; confusing queueing delays with seek latency.

Final Answer:

is used for analyzing device busy problems