Data Counters

vCenter Server systems and hosts use data counters to query for statistics. A data counter is a unit of information relevant to a given object.

For example, network metrics for a virtual machine include one counter that tracks the rate at which data is transmitted and another counter that tracks the rate at which data is received across a NIC instance.

Each data counter is comprised of several attributes that are used to determine the statistical value collected. Table 2 lists the data counter attributes.

Table 2. Data Counter Attributes

Attribute	Description
Unit of measurement	How the statistic quantity is measured. ■ KiloBytes (KB) – 1024 bytes ■ KiloBytes per second (KBps) – 1024 bytes per second ■ Kilobits (kb) – 1000 bits ■ Kilobits per second (kbps) – 1000 bits per second ■ MegaBytes (MB) ■ MegaBytes per second (MBps) ■ Megabits (mb) ■ Megabits per second (mbps) ■ MegaHertz (MHz) ■ Microseconds (µs) ■ Milliseconds (ms) ■ Number (#) ■ Percentage (%) ■ Seconds (s)
Description	Text description of the data counter.
Statistics type	Measurement used during the statistics interval. Related to the unit of measurement. ■ Rate – Value over the current statistics interval ■ Delta – Change from previous statistics interval ■ Absolute – Absolute value, independent of the statistics interval
Rollup Type	Calculation method used during the statistics interval to roll up data. This determines the type of statistical values that are returned for the counter. One of: ■ Average – Data collected during the interval is aggregated and averaged. ■ Minimum – The minimum value is rolled up. ■ Maximum – The maximum value is rolled up. The Minimum and Maximum values are collected and displayed only in collection level 4. Minimum and maximum rollup types are used to capture peaks in data during the interval. For real-time data, the value is the current minimum or current maximum. For historical data, the value is the average minimum or average maximum. Minimum and maximum rollup types are denoted in the collection level value by parentheses. For example, the following information for the CPU usage chart shows that the average value is calculated and displayed at collection level 1 and the minimum and maximum values are displayed at collection level 4. ■ Counter: usage ■ Stats Type: Rate ■ Unit: Percentage (%) ■ Rollup Type: Average (Minimum/Maximum) ■ Collection Level: 1 (4) ■ Summation – Data collected is summed. The measurement displayed in the chart represents the sum of data collected during the interval. ■ Latest – Data collected during the interval is a set value. The value displayed in the performance charts represents the current value.
Collection level	Number of data counters used to collect statistics. Collection levels range from 1 to 4, with 4 having the most counters.