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I run PRTG on VMware. How can I obtain best performance?



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When running PRTG on a virtual machine, for example, VMware, I encounter some performance and stability issues. Are there recommendations for settings when running PRTG on a VM?

checklist important performance prtg recommendations settings virtual-machine vm vmware

Created on Mar 18, 2013 3:03:05 PM by  Gerald Schoch [Paessler Support]

Last change on Mar 19, 2013 9:10:49 AM by  Daniel Zobel [Paessler Support]

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This article applies to PRTG Network Monitor 12 or later

Checklist for Running PRTG on VMware

Important notice: We recommend that you use a dedicated physical machine to run both the PRTG core server or PRTG remote probes. If you run the PRTG core server on a virtual machine, we strongly recommend that you stay below 5,000 sensors for performance reasons. Unfortunately, we cannot offer in-depth technical support regarding performance and stability problems for PRTG installations on virtual machines that run with more than 5,000 sensors in total. In this case, please migrate PRTG to one or more machines, preferably physical ones.

General Recommendations

However, if you run PRTG on a virtual machine, please keep in mind the following conditions for acceptable performance:

  • Do not use more than 5,000 sensors.
  • For a cluster setup, divide these values by the number of cluster nodes when running the PRTG core server on a virtual machine.
  • Use a really fast storage: A physical storage directly on the PRTG core server is much faster than storage over the network. On the other hand, network storages can be configured in failover mode: If an ESX server fails, the storage will be moved immediately to another one, so it has little impact on PRTG. Please evaluate the advantages against the disadvantages in your setup.
  • Use long sensor intervals of 15 minutes or more.
  • Ensure that clocks are synchronized: On your VM’s guest operating system, VMware Tools should be installed. Ensure that the system time of VMware is synchronized with the time of the host system or an NTP server, but not both. Check that the host syncs time correctly as well. If clocks are unsynchronized, PRTG probes might be unable to connect, as well as HTTP requests to the PRTG webserver can fail, mainly when using HTTPS. In addition, HTTP sensors can fail (especially when monitoring websites via HTTPS) if the time difference between the system running the probe and the target system is too big. Running the Network Time Protocol (NTP) client on the ESX host and the domain controller can keep clocks synchronized over a network.
  • Use VMware 5 to reduce resource issues. Avoid earlier VMware versions
  • Consider that PRTG creates a lot of input/output (I/O) on your system. It can be the case that other VMs interfere with this traffic. To reduce related bottlenecks, use VMware 5. Avoid earlier VMware versions.
  • Configure your VM to have the CPU cores on the same CPU socket. CPU cores on individual sockets may result in serious performance issues. Scheduling threads over different sockets in such a configuration has a high impact on the operating system so that Windows may not do it at all. This means that PRTG can only use 1 CPU with 1 core in this configuration and cannot work properly.
  • Use a VMXNET (original, 2 or 3) network adapter instead of an emulated one (Vlance, e1000x). You must install or update the VMware Tools on the guest OS to have a driver for the VMXNET network adapters available.

Resource Management

Resource management for your virtual machines is more important the bigger your environment is. There are more performance issues with environments running several VMs.

In order to run PRTG on a VM, consider to customize resource allocation settings to obtain the best possible performance for the VM with PRTG. This issue especially concerns the resource types CPU, memory, and storage.

For detailed information about resource management for VMware, please make yourself familiar with the official documentation: vSphere Resource Management

You have the following options to increase the performance of the virtual machine PRTG is running on:

  • Ensure that a fix amount of the physical memory of your host server is assigned to the virtual machine running PRTG. We recommend 8 GB or more.
  • For best performance of your PRTG server(s), ensure that your host system always assigns resources to the virtual machine running PRTG with higher priority than to other VMs, depending on your needs.

To achieve this, set Resource Allocation Shares to High for the virtual machine running PRTG, and guarantee a minimum allocation for this VM with Resource Allocation Reservation.

Also keep in mind memory ballooning and over-provisioning:

  • Memory ballooning: This is a memory over-commitment mechanism for multiple virtual machines while they are running. Memory that was allocated to a virtual machine can be given to another virtual machine without changing settings manually. This can affect performance and stability of PRTG. To avoid this issue, customize your VMware settings as described above.
  • Over-provisioning: This is the difference between the physical capacity of CPU and memory and the logical capacity through the operating system as available for the user. The host can give the VMs more CPU or memory than physically available. Over-provisioning can lead to resource bottlenecks and can affect PRTG’s performance and stability. For this reason, customize your VMware settings as described above.

Potential Problems with VMXNET 3 Virtual NIC Cards and Hardware Offload Engine

We have noticed situations where customers used the VMXNET 3 virtual network cards and encountered corrupted UDP packets ("Bad checksum") related to the hardware offload engine used in VMware NIC (i.e., disable TCP/UDP checksum offloading on the network adapter from within the guest operating systems). This resulted in UDP packets loss, unstable SNMP monitoring, and other effects.

Following is the VMware knowledge base article about this particular NIC driver (browse to section VMXNET 3):


Please consider that there is no perfect recommendation for settings when running PRTG in a virtual environment. But if you run PRTG on VMware systems, follow this checklist to get an acceptable performance and stability of PRTG.

Created on Mar 18, 2013 3:26:17 PM by  Gerald Schoch [Paessler Support]

Last change on Feb 24, 2017 10:18:33 AM by  Gerald Schoch [Paessler Support]



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Created on Apr 2, 2013 6:20:27 AM by  rethu45 (0)



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Please take notice that this post is based on our/my experiences, and our environment. For a couple details of our environment look below.

Some general recommendations:

  • Proper setup of your virtual environment with tuning is mandatory. Look at your vendors (optimization) recommendations about virtual environments.
  • Take time to think about seperating sensors over several probes. Balancing the load over several probes, so DRS can vMotion the probe to the most suitable host.
  • First, monitor the datacenter hardware layer, especially what maybe potential bottlenecks. Load on storage controllers, networking on physical machines, switches, load on physical machines, etc. etc. This is usefull if you build up the PRTG environment, and resources like storage performance may become an issue. Then you're aware of that.
  • Second, start monitoring the virtual servers. Build it up -controlled- and keep track of the performance of the whole PRTG environment and the physical environment.

In our case:

  • HP did a health check on our environment. We have an optimized virtual infrastructure.
  • We've split up the hardware vlan and the virtual machines vlan on 2 seperate remote probes.
  • Also we split up our core application and Citrix to 2 seperated remote probes.
  • Initially we install PRTG Remote Probe on a Win2008R2 with 1 Gb memory. Based on system health and the warnings of the probe sensors we increase resources.
  • The probes with virtual Windows servers have 2 groups, the Server Layer and the Application Layer. The server layer is based on a device template, the application layer has additional sensors.

About our environment:

- running VMware vSphere 5.1
- using 2 HP enclosures with HP blades, interlinked
- HP VirtualConnect, fibre connected to SAN switches and fibre connected to LAN
- HP EVA SAN storage, fibre connected to SAN switches
- VMware resource pool: normal shares, no reservations, no limitations
- VM's: VMXNET 3 nic drivers, Resources of VM's: default (memory/cpu/disk)
- PRTG Network Monitor x64
- approx. 200 vm's ( 130x win2008r2 / 70x 2003r2)
- 13504 sensors

Primary and failover (virtual) cluster node: Win 2008 R2 64-bit, normal shares, 2 vcpu, 6 Gb internal memory. 4 virtual probes within the datacenter: Win 2008 R2 64-bit, normal shares, 2 vcpu, 1 Gb internal memory.

Our scanning interval is 60 seconds. We do not use dedicated storage. The 4 virtual probes have: 388, 23, 4289 and 5101 sensors.

sensortypes: 36x esxserverhealthsensorextern, 36x esxserversensorextern, 3x exe, 21x exexml, 1x file, 5x folder, 5x ftp, 70x http, 15x httpadvanced, 25x ldap, 521x ping, 344x port, 29x probestate, 2x ptfadsreplfailure, 23x ptfhttpxmlrestvalue, 104x ptfloggedinusers, 4x ptfpingjitter, 3x ptfscheduledtaskxml, 10x remotedesktop, 1x smbdiskspace, 2x smtp, 1x sniffercustom, 2x snifferheader, 125x snmpciscosystemhealth, 182x snmpcpu, 207x snmpcustom, 6x snmpcustomstring, 479x snmpdiskfree, 2x snmphpphysicaldisk, 3x snmphpsystemhealth, 7593x snmplibrary, 366x snmpmemory, 16x snmprmon, 686x snmptraffic, 1x snmptrap, 185x snmpuptime, 2x sntp, 48x sshesxdiskfreev2, 1x syslog, 29x systemstate, 3x winapieventlog, 27x wmicustom, 43x wmidiskspace, 193x wmieventlog, 6x wmiexchangeserver, 3x wmiexchangetransportqueues, 12x wmilogicaldisk, 17x wmimemory, 47x wminetwork, 16x wmipagefile, 3x wmiphysicaldisk, 2x wmiprocess, 18x wmiprocessor, 285x wmiservice, 141x wmishare, 10x wmisqlserver2008, 77x wmiuptime, 201x wmiutctime, 1209x wmivitalsystemdata, 8x wmivolume

This is a good working virtual PRTG configuration, fully on VMware.

I know, this is against some of the recommendations above. In our case it works, but if it will work in your case. I can't say :)

Please give your comments, experiences to this post. Or can you tell your configuration, and what are your recommendations ?

Created on May 8, 2013 9:15:12 PM by  Pieter Reitsma (130) 1 1

Last change on May 10, 2013 8:33:03 AM by  Daniel Zobel [Paessler Support]



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Thank You.

Created on Mar 24, 2015 12:36:35 PM by  mehmet_sami (0)



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Thanks for your great "real-world" recap of your virtualized environment. I would be interested to learn a few things if you are still actively participating in this forum:

  1. Has your environment grown? What is your sensor total now?
  2. Have you run into any performance issues with this many sensors over the past 2+ years from your initial post?
  3. What speed HDDs do you utilize in the HP SANs? 10K SAS? 15K SCSI? SSD?

We are planning a massive deployment and are interested to hear stories of others' environments that push the limits, both virtualized and on physical hardware?


Created on Jun 11, 2015 11:08:46 PM by  Todd Pettinger (0) 1

Last change on Jun 12, 2015 7:08:11 AM by  Torsten Lindner [Paessler Support]



Your Vote:



Hello Todd,

My recap was more than 2 years ago. A lot of changes the last years, in IT and personally. I've changed jobs, so current status of the monitoring environment is not clear to me. Also the storage environment has changed. So I can't give a good answer to your 3 questions.

My point was that if your monitor the health of the probes, and make one combined sensor with the health of multiple probes you know the status. And then you can exceed the recommendations of Paessler.

I you want to push limits of an environment you could use Login VSI performance testing tool: . Also you can take a look at XanGati and ControlUp.


Created on Jun 12, 2015 1:00:12 PM by  Pieter Reitsma (130) 1 1

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