8.35. VBoxManage metrics

This command supports monitoring the usage of system resources. Resources are represented by various metrics associated with the host system or a particular VM. For example, the host system has a CPU/Load/User metric that shows the percentage of time CPUs spend executing in user mode over a specific sampling period.

Metric data is collected and retained internally; it may be retrieved at any time with the VBoxManage metrics query subcommand. The data is available as long as the background VBoxSVC process is alive. That process terminates shortly after all VMs and frontends have been closed.

By default no metrics are collected at all. Metrics collection does not start until VBoxManage metrics setup is invoked with a proper sampling interval and the number of metrics to be retained. The interval is measured in seconds. For example, to enable collecting the host processor and memory usage metrics every second and keeping the 5 most current samples, the following command can be used:

VBoxManage metrics setup --period 1 --samples 5 host CPU/Load,RAM/Usage

Metric collection can only be enabled for started VMs. Collected data and collection settings for a particular VM will disappear as soon as it shuts down. Use VBoxManage metrics list subcommand to see which metrics are currently available. You can also use --list option with any subcommand that modifies metric settings to find out which metrics were affected.

Note that the VBoxManage metrics setup subcommand discards all samples that may have been previously collected for the specified set of objects and metrics.

To enable or disable metrics collection without discarding the data VBoxManage metrics enable and VBoxManage metrics disable subcommands can be used. Note that these subcommands expect metrics, not submetrics, like CPU/Load or RAM/Usage as parameters. In other words enabling CPU/Load/User while disabling CPU/Load/Kernel is not supported.

The host and VMs have different sets of associated metrics. Available metrics can be listed with VBoxManage metrics list subcommand.

A complete metric name may include an aggregate function. The name has the following form: Category/Metric[/SubMetric][:aggregate]. For example, RAM/Usage/Free:min stands for the minimum amount of available memory over all retained data if applied to the host object.

Subcommands may apply to all objects and metrics or can be limited to one object or/and a list of metrics. If no objects or metrics are given in the parameters, the subcommands will apply to all available metrics of all objects. You may use an asterisk ("*") to explicitly specify that the command should be applied to all objects or metrics. Use "host" as the object name to limit the scope of the command to host-related metrics. To limit the scope to a subset of metrics, use a metric list with names separated by commas.

For example, to query metric data on the CPU time spent in user and kernel modes by the virtual machine named "test", you can use the following command:

VBoxManage metrics query test CPU/Load/User,CPU/Load/Kernel

The following list summarizes the available subcommands: