Host System Utilization

Note: Performance varies by environment and you may or may not see similar results.

Generally, a Tenable Nessus Agent uses 50 MB to 60 MB of RAM (all pageable). A Tenable Nessus Agent uses almost no CPU while idle, but is designed to use up to 100% of the CPU when available during jobs.

To measure network utilization when uploading results, Tenable monitored agent uploads intoTenable Vulnerability Management over a seven-day period. Of over 36,000 uploads observed:

• The average size was 1.6 MB.
• The largest size was 37 MB.
• 90% of uploads were 2.2 MB or less.
• 99% of uploads were 5 MB or less.

• Tenable Nessus Agent processes consume between 45 MB and 60 MB of RAM when dormant, depending on the operating system.

  Note: In Linux environments, the Hugepagesize value plays a significant role in the usage shown by the systemctl status nessusagent command. The shown usage not only includes the agent processes' RAM consumption but also any cached data that would be stored on disk if the system experiences memory pressure.

  For example, x86-64-based Linux systems typically exhibit a total usage ranging from 200 MB to 600 MB with the default Hugepagesize value of 2048 kB. ARM64-based Linux systems with a larger Hugepagesize value show correspondingly high memory usage (for example, the usage shows as multiple gigabytes with a default Hugepagesize of 512 M).

• The Watchdog service consumes 3 MB.
• Plugins consume approximately 300 MB of disk space (varies based on operating system). However, under certain conditions, disk or memory usage can spike up to 1 GB or more.
• Scan results from Tenable Nessus Agents to Tenable Nessus Manager and Tenable Vulnerability Management range between 2-3 MB.
• Check-in frequency starts at 30 seconds and is adjusted by Tenable Nessus Manager orTenable Vulnerability Management based on the management system load (number of agents).