Performance Intervals

The PerformanceManager defines performance intervals which specify the period of time between collection events, how much data will be collected, and how long the collected data will be saved.

■	An ESXi server has a built-in performance interval that produces discrete data values from counter instances sampled every 20 seconds. The server will maintain this instance data for one hour.

■	Additional data collection is specified by historical performance intervals which produce data aggregated from counter instances according to the individual intervals.

The PerformanceManager.historicalInterval property is an array of PerfInterval objects. The following table lists the PerfInterval properties.

PerfInterval Properties 

Property	Description
samplingPeriod	Number of seconds for the interval. You can modify this property on a vCenter Server only.
length	Period of time for which the server will save the data that it collects. You can modify this property on a vCenter Server only.
level	Level at which the Server collects data. The interval level corresponds to the performance counter level (PerfCounterInfo.level). The Server will collect data for all counters with levels that match PerfInterval.level, and for all counters with levels lower than PerfInterval.level. You can modify this property on a vCenter Server only.
enable	Enable/disable performance data collection. You can modify this property on a vCenter Server only.
key	Unique identifier for the interval. You cannot modify this property.
name	Label for the historical interval; one of the following strings: ■ “Past Day” ■ “Past Week” ■ “Past Month” ■ “Past Year” The PerformanceManager uses the samplingPeriod, level, and length properties to determine its collection behavior. It does not interpret the name string. You cannot modify this property.

ESXi Server Performance Intervals

An ESXi server collects performance data for each performance counter every 20 seconds. The PerformanceManager.historicalInterval array for an ESXi Server contains a single, readonly PerfInterval object that specifies rollup data collection every 5 minutes. You cannot retrieve 5-minute rollup data from an ESXi Server directly. You can use a vCenter Server connection to obtain 5-minute rollup data for an ESXi Server. The following table shows the historical interval property values on an ESXi server. You cannot modify this performance interval.

Values of PerfInterval Data Object from an ESXi System 

Property	Value	Description
key	1	Numeric identifier for the PerfInterval.
name	PastDay	Name of the PerfInterval.
samplingPeriod	300	Time interval between data sampling events.
length	129600	Number of seconds that statistics associated with the interval are kept by the vCenter Server.
enabled	true	This PerfInterval is enabled on the system.
level	null	Statistics collection level. For an ESXi system, this property is null. The PerfInterval object on an ESXi system defines the baseline interval.

vCenter Server Performance Intervals

A vCenter Server system aggregates performance data from all ESXi systems that it manages. The amount of data aggregated depends on the level setting configured for the vCenter Server. The level settings are reflected in the PerformanceManager.historicalInterval property for the vCenter Server system. historicalInterval is an array of PerfInterval data objects that define four different level settings, 1 through 4.

Values of PerfInterval Data Objects from a vCenter Server System lists the default values for the performance intervals on a vCenter Server system.

Values of PerfInterval Data Objects from a vCenter Server System 

Key	Name	Sampling Period	Length	Enabled	Level
1	Past Day	300	86400	TRUE	1
2	Past Week	1800	604800	TRUE	1
3	Past Month	7200	2592000	TRUE	1
4	Past Year	86400	31536000	TRUE	1

By default, the collection level is set to 1 for each of the four intervals. Using the default level, a vCenter Server will collect data for all performance counters that specify collection level 1. Using the default length value, a vCenter Server will save collection data for the following time periods:

■	5-minute samples for the past day

■	30-minute samples for the past week

■	2-hour samples for the past month

■	1-day samples for the past year

Data older than a year is purged from the vCenter Server database.