Which statement about queue depth is true?

Which statement about queue depth is true?

• A. It is the latency per operation.
• B. It is the maximum size of a single I/O request.
• C. It is the total data transferred per second.
• D. It represents the number of outstanding I/O requests.

Answer: (D)

Queue depth is the number of outstanding I/O requests that have been issued to the storage system but not yet completed. It reflects how many operations are queued or in flight at a given moment. A higher queue depth can improve utilization and IOPS by keeping the storage device busy, but if it grows beyond what the device can handle efficiently, latency per request can increase as more requests line up. This concept is distinct from latency per operation, which measures the time for a single request, from the maximum size of one I/O request, and from the total data transferred per second, which describes throughput.

Queue depth is the number of outstanding I/O requests that have been issued to the storage system but not yet completed. It reflects how many operations are queued or in flight at a given moment. A higher queue depth can improve utilization and IOPS by keeping the storage device busy, but if it grows beyond what the device can handle efficiently, latency per request can increase as more requests line up. This concept is distinct from latency per operation, which measures the time for a single request, from the maximum size of one I/O request, and from the total data transferred per second, which describes throughput.