iostat

Overview

The iostat command reports CPU statistics and input/output statistics for devices and partitions. It’s useful for monitoring system input/output device loading.

Syntax

iostat [options] [interval [count]]

Common Options

Option Description
-c CPU utilization
-d Device utilization
-h Human readable
-k In kilobytes
-m In megabytes
-N Device mapper names
-p Partition stats
-t Print time
-x Extended stats
-y Since boot
-z Omit idle

Output Fields

Field Description
tps Transfers per second
kB_read/s Kilobytes read per second
kB_wrtn/s Kilobytes written per second
kB_read Total kilobytes read
kB_wrtn Total kilobytes written
await Average wait time
svctm Service time
%util Utilization

Key Use Cases

  1. IO monitoring
  2. Disk performance
  3. System analysis
  4. Capacity planning
  5. Troubleshooting

Examples with Explanations

Example 1: Basic Usage

iostat

Basic statistics

Example 2: Extended Stats

iostat -x

Detailed information

Example 3: Continuous

iostat 2 10

Every 2s, 10 times

Common Usage Patterns

  1. Device monitoring:

    iostat -d

  2. Extended info:

    iostat -xz

  3. Specific device:

    iostat -p sda

Performance Metrics

  1. Throughput
  2. Response time
  3. Queue length
  4. Utilization
  5. Service time

Additional Resources

Best Practices

  1. Regular monitoring
  2. Check trends
  3. Use intervals
  4. Document baselines
  5. Compare devices

Performance Analysis

  1. IO patterns
  2. Device load
  3. Queue depth
  4. Response times
  5. Bandwidth usage

Troubleshooting

  1. IO bottlenecks
  2. Device saturation
  3. Queue buildup
  4. High latency
  5. Low throughput

Common Issues

  1. Disk contention
  2. Queue saturation
  3. High wait times
  4. Device overload
  5. Poor performance