vmstat

Overview

The vmstat command reports virtual memory statistics. It provides information about processes, memory, paging, block IO, traps, and CPU activity.

Syntax

vmstat [options] [delay [count]]

Common Options

Option Description
-a Active/inactive memory
-f Fork statistics
-m Slab info
-n Header once
-s Event counters
-d Disk statistics
-p partition Partition stats
-S unit Output units
-t Timestamp
-w Wide output

Output Fields

Field Description
r Running processes
b Blocked processes
swpd Virtual memory
free Idle memory
buff Buffer memory
cache Cache memory
si Swapped in
so Swapped out
bi Blocks in
bo Blocks out
in Interrupts
cs Context switches
us User time
sy System time
id Idle time
wa IO wait
st Stolen time

Key Use Cases

  1. Memory monitoring
  2. System performance
  3. IO analysis
  4. CPU utilization
  5. Process states

Examples with Explanations

Example 1: Basic Usage

vmstat

Current statistics

Example 2: Continuous

vmstat 2 10

Every 2s, 10 times

Example 3: Disk Stats

vmstat -d

Show disk statistics

Common Usage Patterns

  1. Real-time monitoring:

    vmstat 1

  2. Memory details:

    vmstat -s

  3. Disk activity:

    vmstat -d -p /dev/sda1

Additional Resources

Best Practices

  1. Regular monitoring
  2. Set intervals
  3. Compare trends
  4. Document baselines
  5. Check all metrics

Performance Analysis

  1. Memory usage
  2. CPU utilization
  3. IO activity
  4. Process states
  5. System load

Troubleshooting

  1. High memory use
  2. Swap activity
  3. IO bottlenecks
  4. CPU saturation
  5. Process blocking

Common Issues

  1. Memory pressure
  2. Swap thrashing
  3. IO congestion
  4. CPU contention
  5. Process queuing