**License: Free** - No license required. Available in all tiers.

Memory Probe#

The Memory probe monitors system memory and swap usage across all major operating systems, providing comprehensive metrics for physical memory, cache, buffers, and page file utilization.

Quick Start#

Basic Configuration#

probes:
  - name: memory
    params:
      interval: 30  # Collection interval in seconds (default: 30)

Minimal Configuration#

probes:
  - name: memory
    params: {}

The Memory probe requires no mandatory parameters and works out-of-the-box with default settings.

Supported Platforms#

• Windows: Windows Server 2012+ / Windows 10+
• Linux: All modern distributions (Ubuntu, RHEL, CentOS, Debian, etc.)
• macOS: macOS 10.13+
• BSD: FreeBSD, OpenBSD, NetBSD

Platform-specific metrics are automatically detected and collected based on the operating system.

Key Metrics Summary#

Cross-Platform Metrics#

Unix/Linux/macOS Specific#

Windows Specific#

Configuration Parameters#

Example Configurations#

High-frequency monitoring (every 10 seconds):

probes:
  - name: memory
    params:
      interval: 10

Standard monitoring (every minute):

probes:
  - name: memory
    params:
      interval: 60

Monitoring Tool Integration#

PRTG Network Monitor#

Access memory metrics in PRTG JSON format:

# All memory metrics
curl http://localhost:8080/api/{agentkey}/prtg/metrics

# Configure PRTG HTTP Advanced Sensor:
# - URL: http://agent-host:8080/api/{agentkey}/prtg/metrics
# - Method: POST
# - Request body: {"probe": "memory"}

PRTG Channels Available:

• Memory Available (bytes)
• Memory Used (%)
• Memory Total (bytes)
• Swap Used (%)
• Page Faults/sec (Windows)
• Cache Memory (bytes)

Nagios/Icinga#

Access memory metrics in Nagios format:

# All memory metrics with performance data
curl http://localhost:8080/api/{agentkey}/nagios/metrics?probe=memory

# Example output:
# OK - Memory monitoring active | memory_used_percent=65.2%;80;90 swap_used_percent=12.5%;50;75

Nagios Performance Data:

• memory_used_percent - Memory usage with 80% warning, 90% critical
• swap_used_percent - Swap usage with 50% warning, 75% critical
• memory_available - Available memory in bytes

Grafana/Prometheus#

Access metrics in Prometheus-compatible format:

# Prometheus format
curl http://localhost:8080/api/{agentkey}/prometheus/metrics

# Example output:
# memory_used_percent{hostname="server01"} 65.2
# memory_available{hostname="server01"} 8589934592
# swap_used_percent{hostname="server01"} 12.5

Web Interface#

View memory metrics in the built-in dashboard:

http://localhost:8080/web/{agentkey}/dashboard

Features:

• Real-time memory usage visualization
• Memory breakdown (used, cached, buffers, free)
• Swap usage monitoring
• Historical memory trends

Use Cases#

Memory Leak Detection#

Monitor memory usage over time to identify:

• Gradual memory consumption increase
• Applications not releasing memory
• Kernel memory leaks
• Cache growth patterns

Capacity Planning#

Track memory trends to plan:

• When to add more RAM
• Application memory requirements
• Virtual machine sizing
• Container memory limits

Performance Optimization#

Analyze memory usage to:

• Identify memory-constrained applications
• Optimize cache utilization
• Reduce swap usage
• Balance memory allocation

System Health Monitoring#

Monitor memory health:

• Available memory for applications
• Swap activity (performance impact)
• Page fault rates (Windows)
• Memory pressure indicators

Troubleshooting#

No Metrics Collected#

Check probe status:

# View agent logs with memory probe debugging
./agent run --authentication-key YOUR_KEY --verbose --debug-modules probe.memory

Verify probe is enabled:

# Check configuration
cat agent-config.yaml | grep -A5 "name: memory"

Windows: PDH Counter Errors#

Symptom: Error messages about Performance Data Helper (PDH) counters

Solution:

1. Verify Performance Counter service is running:

   Get-Service | Where-Object {$_.Name -eq "PerfHost"}

2. Rebuild Performance Counters:

   lodctr /R

3. Check Windows Event Log for PDH errors

Unix/Linux: Permission Denied#

Symptom: Cannot read /proc/meminfo or system files

Solution: Run the agent with appropriate permissions:

# Option 1: Run as root
sudo ./agent run --authentication-key YOUR_KEY

# Option 2: Grant capabilities (Linux)
sudo setcap cap_sys_admin=eip ./agent

High Memory Usage from Agent#

Symptom: Agent itself consuming significant memory

Solution:

1. Increase collection interval:

   - name: memory
     params:
       interval: 60  # Collect every minute instead of 30 seconds

2. Check for memory leaks in other probes

3. Review system available memory

Missing Swap Metrics#

Unix/Linux: Verify swap is configured:

# Check swap status
swapon --show

# View swap usage
free -h

Windows: Verify page file is configured:

# Check page file settings
Get-CimInstance -ClassName Win32_PageFileUsage

Performance Considerations#

Collection Overhead#

The Memory probe has minimal overhead:

• Windows: ~5ms per collection (PDH counters)
• Unix/Linux: ~20ms per collection (gopsutil library)
• macOS: ~15ms per collection (system calls)

Memory Usage#

Typical memory footprint per collection:

• Base probe: ~200 KB
• Metrics storage: ~10 KB per collection
• Example: 30-second interval = ~500 KB total

Recommended Intervals#

Advanced Configuration#

Multi-Instance Monitoring#

Monitor memory with different collection frequencies:

probes:
  - name: memory_realtime
    params:
      interval: 10

  - name: memory_trending
    params:
      interval: 300

Note: This will create duplicate metrics. Use unique probe names for different collection intervals.

Integration with Other Probes#

Correlate memory metrics with other system metrics:

probes:
  - name: cpu
    params:
      interval: 30

  - name: memory
    params:
      interval: 30

  - name: logicaldisk
    params:
      interval: 60

This provides comprehensive system monitoring with aligned collection intervals.

Authentication#

The Memory probe requires no authentication as it collects local system metrics only.

Requirements#

Windows#

• Windows Server 2012+ or Windows 10+
• Performance Counter service enabled
• No special permissions required (runs as service account)

Linux/Unix/macOS#

• Read access to /proc/meminfo (Linux)
• Read access to /proc/vmstat (Linux)
• System information APIs (macOS, BSD)

Network#

• No network access required (local metrics only)
• HTTP strategy required for remote access to metrics