iostat Command Guide for Linux: 20 Practical Examples for CPU and Disk I/O Troubleshooting

The iostat command helps Linux and Unix operators quickly understand CPU usage and disk I/O behavior. If you troubleshoot slow applications, storage latency, or noisy hosts, this guide gives you practical commands and a repeatable workflow.

Originally published on 2015-12-12; fully revised and updated.

What iostat reports

iostat (part of the sysstat package on Linux) reports two main categories:

• CPU statistics (overall CPU state percentages such as user, system, idle, and iowait).
• Device I/O statistics (throughput, operation rates, queueing, and utilization for block devices and partitions).

Linux builds usually read from kernel-provided interfaces such as /proc/stat, /proc/diskstats, /proc/partitions (older kernels), and /sys.

iostat vs related system tools

Install and verify iostat on Linux

On most Linux distributions, iostat is shipped by sysstat. You usually do not need a root shell for reading stats, but package installation needs elevated privileges.

# Check whether iostat is already installed
which iostat

# Show version (sysstat version)
iostat -V

# RHEL/CentOS/Amazon Linux
sudo yum install -y sysstat

# Fedora and newer RHEL-family systems
sudo dnf install -y sysstat

# Debian/Ubuntu
sudo apt-get update && sudo apt-get install -y sysstat

# RPM-based verification
rpm -qa | grep -i sysstatCode language: PHP (php)

Workflow: triage storage bottlenecks with iostat

flowchart TD
    A[Alert high app latency] --> B[Run iostat -x 1 5]
    B --> C{High await or high util}
    C -- no --> D[Check CPU memory network with mpstat vmstat]
    C -- yes --> E[Identify busiest device]
    E --> F[Correlate with process tools]
    F --> G[Apply fix tune rebalance or scale]
    G --> H[Re-run iostat and validate]

20 practical iostat commands (Linux sysstat)

The following examples are Linux-focused. Option availability can vary by sysstat version and by Unix flavor, so confirm with man iostat on your host.

# Example live triage session
iostat -x -m 1 10
iostat -p ALL 1 5
mpstat 1 5
vmstat 1 5Code language: PHP (php)

How to read key extended fields

Compatibility notes across Linux and Unix variants

Older tutorials often mix Linux and non-Linux iostat options. For example, some Unix variants document flags not present in current Linux sysstat builds. Always validate command syntax with the local man page before automating.

Best practices

• Capture repeated samples (interval count) instead of relying on one snapshot.
• Use -x during incidents to see latency and queue behavior, not just throughput.
• Correlate host-level metrics with process-level tools (pidstat, iotop) before changing configuration.
• Record timestamps (-t) when comparing with application and database logs.
• Treat field names as version-dependent; confirm on each distribution baseline.

Rajesh Kumar

I’m Rajesh Kumar, a DevOps, SRE, DevSecOps, Cloud, and Platform Engineering expert passionate about sharing practical knowledge, real-world experiences, and industry best practices. I have worked at Cotocus and regularly write about technology, travel, investing, health, product reviews, and digital marketing through my various platforms.

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