What is the primary purpose of the iostat command in Linux?

• A. Display I/O statistics for devices and partitions
• B. Display memory usage
• C. Show CPU temperature
• D. List active processes

Answer: (A)

iostat reports I/O statistics for storage devices and partitions. The main idea is to show how busy the disks are and how fast data is being read or written, along with how long I/O requests are waiting. This helps you identify disk bottlenecks and assess performance trends, which is essential for tuning systems or diagnosing slow I/O. You can get per-device statistics, extended metrics like throughput (kB/s or MB/s), IOPS, and utilization (%util), and you can run it periodically to monitor changes. It’s different from memory tools (which show RAM usage), CPU temperature tools, or process listing tools. For example, using extended stats with iostat -x reveals detailed per-device metrics such as await and util, aiding deeper analysis.