Understanding Time Ranges and Data Intervals

The time range in Performance Analysis history mode is built on a pyramidal model of granularity, such that more recent data is available in smaller discrete time units (that is, higher granularity) than data from the more distant past. For example, in the following default configuration:

Note: Yesterday, Previous Week, and Previous Month are not time periods relative to the moment of definition; rather they represent, respectively, the previous calendar day (from 00:00 to 23:59), week (Sunday through Saturday), and month (first to month-end).

The data intervals default display is a system-generated optimal resolution in accordance with the displayed range and data availability. StealthCollect supports two models of historical collections (as determined at installation):

• Short term only - Data is stored only up to 90 days. All data in all resolutions is held in data files within the StealthCollect middleware.

• Long term - Data can be stored for an unlimited time period. Data intervals of one and 15 minutes are stored in files because of their quantity. Longer time intervals are stored in the repository, a restriction that limits the period for which this data can be aggregated and archived. The list of available intervals for each time range is derived from the historical collection configuration. The time pyramid configuration (initially set at the time of StealthCollect installation) determines the duration for which each data interval is stored.

Timeline Graph and Data Unavailability

In the above example, Performance Analysis may be unable to display data for a specific period (resulting in a blank display), for one of the following reasons:

• Historical data for the period was not collected because either the database or the StealthCollect agent was down. Verify which one by examining the value of the = 4) BSPSPopupOnMouseOver(event)" class=BSSCPopup id=a2>DB Availability instance level statistic.

• Data Intervals. The requested data intervals cannot be entirely satisfied with the selected data interval. In such cases, grayed out intervals can appear in either or both the display beginning and end. This occurs principally when using dynamic (for example, last day, last week, last month) time frames.