P6 - Monitor Proxmox RAM (Real Memory Usage) with PRTG
PRTG – P6 How to Monitor Proxmox RAM (Real Memory Usage) with PRTG
Memory usage in Proxmox can be misleading if you don’t monitor the real values. Many administrators rely on standard memory sensors, but cached and buffered memory often distort the actual available RAM.
In this tutorial, you will learn how to Monitor Proxmox RAM using real memory values with PRTG Network Monitor. This guide is designed for system administrators who need accurate memory visibility in production and lab environments.
We will configure a custom SNMP script to calculate real available RAM percentage instead of cached memory. PRTG will then display real-time graphs and trigger alerts when memory thresholds are exceeded.
With proper RAM monitoring, you can prevent performance degradation, slow virtual machines, and unexpected crashes.
This setup works perfectly for both home labs and enterprise Proxmox servers.
This video is part of the PRTG Network Monitoring Tutorial Series.
🛠 Step 1: Create Scripts (SNMP Installed in Previous Video)
To Monitor Proxmox RAM accurately, we will create a custom script that calculates the percentage of real available memory.
Create the script:
Insert the following content:
#!/bin/bash
MEM_TOTAL=$(awk '/MemTotal/ {print $2}' /proc/meminfo)
MEM_AVAILABLE=$(awk '/MemAvailable/ {print $2}' /proc/meminfo)
if [ "$MEM_TOTAL" -eq 0 ]; then
echo 0
else
echo $(( MEM_AVAILABLE * 100 / MEM_TOTAL ))
fiGrant execute permissions:
This script reads /proc/meminfo, calculates the real available RAM percentage, and outputs a single numeric value compatible with SNMP.
🌐 Step 2: DECLARE SNMP EXTEND (EXACTLY THE SAME AS CPU TEMP)
Now we integrate the script into SNMP.
Edit the SNMP configuration file:
Add:
Restart SNMP:
The extend directive allows SNMP to expose the script output as an OID that PRTG can query.
🔎 Step 3: GET THE OID (THE CORRECT WAY – DON’T GUESS)
Copy this exact OID (the one with memAvailPct):
Using the exact OID ensures accuracy and avoids incorrect sensor configuration.
📊 Step 4: Add Sensor (SNMP Custom Advanced)
Now switch to PRTG.
Add a new sensor:
Add Sensor → SNMP Custom Advanced
Configure the following:
Channel
RAM Available
OID
Copy this exact OID (the one with memAvailPct):
Unit
Percent
Recommended Warnings
• Lower Warning: < 25 %
• Lower Error: < 15 %
These thresholds ensure:
Warning when available RAM drops below 25%
Error when available RAM drops below 15%
This provides early detection before memory exhaustion affects running virtual machines.
📈 Why You Should Monitor Proxmox RAM Correctly
When you properly Monitor Proxmox RAM, you gain:
📊 Real available memory visibility
🚨 Early low-memory alerts
📈 Accurate performance graphs
🛡 Prevention of VM crashes
⚡ Improved system stability
Traditional memory monitoring may include cached memory as “used,” but Linux aggressively uses memory for caching. Monitoring MemAvailable gives a realistic view of usable RAM.
This is critical in virtualization environments where memory pressure directly impacts multiple virtual machines.
🛡 Best Practices for RAM Monitoring
To maximize accuracy and reliability:
Always monitor MemAvailable instead of free memory
Combine RAM monitoring with CPU Load and Disk I/O
Review historical memory trends weekly
Adjust thresholds based on workload patterns
Ensure SNMP access is restricted by IP
Memory bottlenecks often correlate with high CPU and storage activity.
📌 Final Thoughts
With this configuration, you have successfully implemented an accurate way to Monitor Proxmox RAM using PRTG Network Monitor.
By creating a lightweight script, declaring SNMP extend, using the correct OID, and configuring a Custom Advanced sensor, you now have precise visibility into real available memory.
This proactive monitoring approach helps prevent performance degradation, avoid VM instability, and maintain a reliable virtualization environment.
In the next part of this series, we will continue enhancing Proxmox monitoring with more advanced PRTG configurations for deeper infrastructure insight.
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