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Systems & Data Center · Intermediate

iostat

A Linux sysstat command that reports CPU and per-device I/O statistics such as IOPS, throughput, latency and utilization.

Definition

iostat -x adds extended metrics including r/s, w/s, await (average latency) and %util. High await and %util near 100 indicate a saturated device.

Example

iostat -xz 2 shows extended stats for active devices every two seconds.

Exam tip

%util near 100 percent may be misleading on SSD and NVMe devices that service many requests in parallel; check await too.

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