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Foglight for VMware 5.8 - User and Reference Guide

Using Foglight for VMware
Introducing the virtual infrastructure Navigation basics Interacting with Foglight for VMware VMware Performance Agent configuration
VMware Alarms views VMware Explorer views VMware Modeler views VMware VirtualCenter views VMware Environment views Other views
Agent Rules Cluster Rules Datacenter Rules Datastore Rules Resource Pool Rules ESX Server Rules VirtualCenter Rules Virtual Machine Rules VMW Stale Data Management Rule Virtual Switch Rules
Appendix: Alarm Messages Appendix: Metrics

VMware Performance Agent configuration

The VMware Performance Agent collects data from the virtual infrastructure and sends it to the <Product Name>™ Management Server. The agent keeps track of resource utilization metrics and alerts you when certain pre-defined thresholds are reached.

VMware Performance Agent and Agent Manager configuration

On 64-bit hosts meeting the minimum system requirements, the embedded Agent Manager can be used to run VMware Performance Agents to monitor up to 500 virtual machines. If the total number of virtual machines to be monitored from a single agent host is greater than 500, an Agent Manager should be installed on a separate host.

If additional cartridges and agents are added to the environment, product performance should be monitored and agents moved off of the embedded Agent Manager to reduce the load.


4 GB



4 GB


1 Additional CPUs may be required for larger environments.

Monitoring more than 4000 virtual machines from a single agent host

The Agent Manager JVM usually requires additional memory to monitor more than 4000 virtual machines. The total number of virtual machines is the total from all vCenters that will be monitored from all VMware Performance agents running on the Agent Manager.

The following calculations are guidelines, not hard and fast rules. Memory requirements can vary greatly from installation to installation with similar VM counts. If insufficient memory is configured, the failure mode is easily recognizable: all agents on the Agent Manager host will go into a broken state after the agent(s) were activated for a short period of time, usually within 24 hours. In addition, the Agent Manager log will contain a line similar to the following:

If this is the case, add memory greater than what is shown in the calculations below, in increments of 512 MB until the agents stabilize.

JVM memory requirements for VMware Performance agents are calculated using the following formula:

According to the above formula, monitoring 4000 virtual machines requires 2560 MB of memory:

This is the default setting for agents deployed on 64-bit systems.

Similarly, monitoring 8000 virtual machines requires 4608 MB of memory:

This requires a change in the default Agent Manager settings.

Determine the amount of additional memory required. This will be the total from the last step above minus the default value of 2560 MB. In the example above, this is 4608 MB – 2560 MB = 2048 MB.
On the agent machine, open the baseline.jvmargs.config file for editing. The file is located in the <Agent_Manager_home>/state/default/config directory.
Add the following lines to the memory settings section:

Host system recommendations

When monitoring larger vCenters, the Agent Manager machine hosting the VMware Performance agents should be dedicated to this task. No other Foglight agent types should run on the host and the host should not run any other applications.

Regardless of the values set for JVM memory above, Agent Manager never allocates more than 80% of system memory. So the machine hosting the Agent Manager and VMware Performance Agents must have sufficient memory. Beyond the memory requirements of the Agent Manager, a minimum of 2 GB should be free for the operating system. In the example above for 8000 VMs and an Agent Manager memory requirement of 4608 MB, the host should have a minimum of 6656 MB - the greater of:


If the Agent Manager is configured on a virtual machine, it is recommended that the VM use a memory reservation to ensure maximum performance.

CPU usage on the Agent Manager host is relatively low most of the time. However, usage peaks dramatically during the performance metric collection. This is normal and expected. CPU utilization consistently over 50% is an indication that additional processing power is required. As with memory, usage can vary between different installations with similar numbers of virtual machines. The following guidelines should be followed.

2 CPUs

4 CPUs

add 1 CPU per 1000 VMs – round up when necessary

When the Agent Manager and VMware Performance agents are running on a virtual machine, the VM should be configured with CPU reservation whenever possible to ensure best performance. Lack of processing power on the Agent Manager manifests in missed collections and gaps in the data usually noticeable in various graphs throughout the Foglight for VMware dashboards.

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