sar

Overview

The sar (System Activity Reporter) command collects, reports, and saves system activity information. It provides comprehensive system performance monitoring capabilities.

Syntax

sar [options] [interval [count]]

Common Options

Option Description
-b I/O and transfer rate statistics
-B Paging statistics
-d Block device activity
-n Network statistics
-P Per-processor statistics
-r Memory utilization
-S Swap space utilization
-u CPU utilization
-v Process, inode, file tables
-w System switching activity
-A All statistics
-f file Extract records from file
-o file Save records to file

Key Use Cases

  1. Performance monitoring
  2. System analysis
  3. Resource tracking
  4. Capacity planning
  5. Troubleshooting

Examples with Explanations

Example 1: CPU Usage

sar -u 2 5

Show CPU stats every 2 seconds, 5 times

Example 2: Memory Stats

sar -r

Show memory utilization

Example 3: Network Stats

sar -n DEV

Show network interface statistics

Understanding Output

CPU statistics: - %user: User time - %nice: Nice time - %system: System time - %iowait: I/O wait time - %steal: Time stolen by virtualization - %idle: Idle time

Memory statistics: - kbmemfree: Free memory - kbmemused: Used memory - %memused: Memory used percentage - kbbuffers: Memory used as buffers - kbcached: Memory used as cache

Common Usage Patterns

  1. Daily monitoring:

    sar -A > report.txt

  2. Network analysis:

    sar -n ALL 1

  3. Historical data:

    sar -f /var/log/sa/sa01

Performance Analysis

  • System resource usage
  • Performance bottlenecks
  • Resource trends
  • Capacity issues
  • Historical patterns

Additional Resources

Best Practices

  1. Regular data collection
  2. Historical analysis
  3. Trend monitoring
  4. Alert thresholds
  5. Documentation

Data Collection

  1. Automated collection
  2. Data retention
  3. Report generation
  4. Analysis tools
  5. Storage management