Nagios XI: Troubleshooting High CPU and Memory Usage

Introduction

Nagios XI is a powerful monitoring solution, but in large or complex environments, it may experience high CPU and memory usage. Excessive resource consumption can lead to slow performance, delayed alerts, or even system crashes. This guide will help you identify the root causes and implement effective solutions to optimize Nagios XI’s performance.

Common Causes of High CPU and Memory Usage

1. Too Many Active Checks

• Running a high number of active checks (checks initiated by Nagios XI) can overload CPU resources.
• Symptoms: Slow system response, delayed checks, high CPU usage.

2. Excessive Passive Checks

• A large volume of passive checks (incoming check results from external sources) can cause high memory usage.
• Symptoms: High memory consumption and slow log processing.

3. Database Performance Issues

• The Nagios XI MySQL/MariaDB database stores historical data, and an unoptimized database can slow down queries and consume excessive resources.
• Symptoms: High memory usage, slow reports and queries, and database locking.

4. Log File Overload

• Large or excessive log files in /var/log/nagios and /var/log/httpd can slow down system performance.
• Symptoms: Frequent disk I/O activity, increased CPU, and increased memory usage.

5. Unoptimized Event Handlers and Plugins

• Inefficient custom scripts, event handlers, or third-party plugins can cause excessive resource usage.
• Symptoms: Nagios XI crashing, high CPU spikes and delayed responses.

6. Uncontrolled Notification Storms

• Excessive alert notifications can consume system resources, especially if not properly managed.
• Symptoms: Slow email processing, CPU overload and high RAM usage.

How to Identify Resource Bottlenecks

1. Monitor System Resources

Run the following Linux commands to check CPU and memory usage:

htop

htop

top

top

free -m

free -m

2. Check Nagios XI Processes

Identify resource-heavy processes:

ps aux --sort=-%mem | head -10

ps aux --sort=-%mem | head -10

ps aux --sort=-%cpu | head -10

ps aux --sort=-%cpu | head -10

3. Analyze Nagios Logs

Check for errors or performance issues in logs:

cat /var/log/nagios/nagios.log | grep -i error

cat /var/log/nagios/nagios.log | grep -i error

cat /var/log/httpd/error_log | grep -i nagios

cat /var/log/httpd/error_log | grep -i nagios

4. Review Database Performance

Check MySQL/MariaDB usage:

mysql -u root -p -e "SHOW PROCESSLIST;"

mysql -u root -p -e "SHOW PROCESSLIST;"

du -sh /var/lib/mysql

du -sh /var/lib/mysql

Solutions to Reduce CPU and Memory Usage

1. Optimize Active and Passive Checks

• Reduce check intervals for less critical hosts/services.
• Use passive checks where possible to reduce CPU load.
• Implement service dependencies to avoid redundant checks.

2. Improve Database Performance

• Clean up old data with:

nagiosxi_database_maintenance

nagiosxi_database_maintenance

• Optimize MySQL indexes:

mysqlcheck -o -u root -p --all-databases

mysqlcheck -o -u root -p --all-databases

• Increase MySQL cache sizes in /etc/my.cnf for better performance.

3. Manage Log Files Efficiently

• Set up log rotation using logrotate:

vi /etc/logrotate.d/nagios

vi /etc/logrotate.d/nagios

• Clear large logs regularly:

truncate -s 0 /var/log/nagios/nagios.log

truncate -s 0 /var/log/nagios/nagios.log

4. Optimize Event Handlers and Plugins

• Review custom scripts for inefficiencies.
• Limit the use of CPU-intensive scripts.
• Run plugins in parallel only when necessary.

5. Control Notification Overload

• Configure notification thresholds to prevent excessive alerts.
• Use notification escalations to distribute alerts efficiently.

6. Upgrade Hardware or Scale Nagios XI

1. Add more CPU cores and RAM if the system is underpowered.
2. Distribute checks across multiple Nagios XI servers in large environments.

Conclusion

High CPU and memory usage in Nagios XI can degrade performance and impact monitoring effectiveness. By identifying resource bottlenecks and applying optimization techniques, you can ensure a stable and efficient monitoring environment. Regular maintenance, database tuning, and check optimizations are key to keeping Nagios XI running smoothly.

For persistent issues, consider upgrading hardware or implementing Nagios XI High Availability (HA) to distribute the load.

Need More Help Monitoring? We’ve Got You Covered!

Whether you’re looking for step-by-step YouTube tutorials or community forums, there are plenty of resources available for Nagios users. If you have a specific question or want to learn more about Nagios Solutions, explore these helpful options:

YouTube Tutorial Playlists:

• Nagios XI Tutorials: Watch Here.
• How to Use and Manage Nagios XI: Watch Here.
• How to Monitor Anything with Nagios: Watch Here.

Discover the advantages of Nagios Software by attending webinars or demos.

For specific inquiries about Nagios Solutions, visit the Nagios Support Forum or consider a Nagios Maintenance & Support Plan.

Happy monitoring!