1. CPU Performance

• Current Usage: top, htop, or mpstat
• Load Average: uptime or check the output of top (the three numbers at the top-right).
• Compare the load average to the number of CPU cores (nproc).
• Processes: Monitor high-CPU-consuming processes using top or ps -eo pid,ppid,cmd,%mem,%cpu --sort=-%cpu.

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2. Memory Usage

• Total and Free Memory: free -h or vmstat -s.
• Swap Usage: Check if swap space is being heavily used (free -h or swapon -s).
• Processes Using Most Memory: top or ps -eo pid,ppid,cmd,%mem --sort=-%mem.

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3. Disk Usage

• Available Space: df -h to check disk usage across filesystems.
• Inode Usage: df -i to check inode utilization.
• Disk I/O: iostat, iotop, or dstat.
• Error Messages: Review logs in /var/log/ for any disk-related errors.

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4. Network Performance

• Network Usage: iftop, ip -s link, or netstat.
• Connections: ss or netstat to check open connections and ports.
• Packet Loss/Latency: ping, traceroute, or mtr.
• Bandwidth Monitoring: vnstat, iftop, or nload.

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5. System Logs

• General System Logs: journalctl or /var/log/syslog (for system-wide events).
• Kernel Logs: dmesg or journalctl -k to check for hardware errors or warnings.

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6. Uptime and System Load

• Uptime: uptime command provides server uptime and load averages.
• Load Analysis: Investigate load spikes with sar or atop.

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7. Running Services and Processes

• Service Status: systemctl status <service> or service <service> status.
• Zombie/Unnecessary Processes: ps aux | grep Z to list zombie processes.

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8. Security

• Users Logged In: who, w, or last.
• Unauthorized Logins: Review /var/log/secure or /var/log/auth.log.
• Firewall Rules: iptables -L or ufw status.
• Listening Ports: ss -tuln or netstat -tuln.

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9. Hardware Health

• Temperature and Fan Speed: sensors (part of lm-sensors package).
• RAID Status: Check using mdadm or vendor tools if RAID is configured.

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10. Scheduled Jobs

• Cron Jobs: crontab -l or check /etc/crontab.
• Failures: Examine /var/log/syslog for cron-related logs.

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11. Backup Status

• Backup Logs: Ensure regular backups are occurring as scheduled.
• Verify Integrity: Test restore procedures periodically.

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Automation Tools for Server Health Monitoring

• Nagios, Zabbix, Prometheus, or Datadog for continuous monitoring.
• Custom scripts combining commands like top, df, iostat, and log parsing can provide quick insights.

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By periodically reviewing these parameters, you can ensure the Linux server’s health and address potential issues proactively.