This article applies to PRTG Network Monitor 9 or later

Increasing Maximum Connections for VMware Sensors

If you experience connection failures in your VMware sensors, please change your vCenter settings to accept more connections at the same time. If this is not enough, try spreading your sensors over several (remote) probes.

Usually, you can run 150 VMware sensors in a 5 minute scanning interval without problems in a non-cluster setup.

Install .NET Updates

A reliability and performance update for .NET Framework 4.0 is available as an optional update (see Microsoft Knowledgebase: Reliability Update 2 for the .NET Framework 4 for details).

After installing this update on the machine running your PRTG Probe, you can run

• 300 VMware sensors in a 5 minute scanning interval if your PRTG server (or remote probe) runs on Windows 2008 R2, or
• up to 100 VMware sensors in a 1 minute scanning interval if your PRTG server (or remote probe) runs on on Windows 7.

Change VMware Settings

Open your vSphere Client settings console from the main menu, select Administration | vCenter Server Settings.... In the Advanced Settings section, change the entry for the key Perf.Stats.MaxCollectionThreads (see screenshots below).

Default value is 2. Change it to 16 in order to allow the maximum of possible synchronous connections.

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Spread Sensors Over Several Probes

The VMware system counts incoming connections per IP address/machine from which the requests come from. If you spread your VMware sensors over several remote probes, this also helps increase the connection limit.

A Note for Cluster Setups

If you're running a cluster setup, remote probes cannot be clustered, and therefore all sensors running on remote probes will not be monitored fail-safely. So, in a cluster setup, we recommend you add your most important VMware sensors to the Cluster Probe (for fail-safe monitoring), the others to one or more remote probes. When running VMware sensors on the Cluster Probe, each PRTG node in your cluster will create its own connection to the VMware server(s) to query monitoring data. To minimize load we strongly recommend using a scanning interval of 5 minutes or more.