Network Management
Understanding the calculation of Average Availability in Orion Platform
In this article, it will provide information on how Orion calculates the Average Availability on the Web Console, or in Reports.
First published date
4/27/2022 3:39 AM
Last published date
9/11/2023 9:49 AM
Overview
There are cases when you require to script or to understand how the underlying statistics collected within Orion derive the Average Availability
But using Average function/calculation against the "Availability" column will not yield the same results as Orion.
But using Average function/calculation against the "Availability" column will not yield the same results as Orion.
Product section
Orion Platform
Cause
Calculation of Availability not just involves the "Availability" column, but also involves the "Weight" column.
This column is important in the average availability calculation, as it determines whether an availability value is Current, Hourly, or Daily.
In short, if your Polling Interval for Node Status is 2 minutes, there will be a row of data that will be inserted into the database, which have a "Weight" of 120s (2 minutes) every 2 minutes.
During nightly Database Maintenance (that happens at 2:15am system time by default), Availability records are summarised into Hourly (for records older than 7 days by default) and daily (older than 30 days by default) tables, and the Weight value is changed.
This column is important in the average availability calculation, as it determines whether an availability value is Current, Hourly, or Daily.
In short, if your Polling Interval for Node Status is 2 minutes, there will be a row of data that will be inserted into the database, which have a "Weight" of 120s (2 minutes) every 2 minutes.
During nightly Database Maintenance (that happens at 2:15am system time by default), Availability records are summarised into Hourly (for records older than 7 days by default) and daily (older than 30 days by default) tables, and the Weight value is changed.
Resolution
The calculation used in Orion differs from the simple average calculation.
The typical average calculation is to sum up all the values within the filtered period and divide it by the number of data points used to sum.
e.g.
10, 11, 12, 56, 66
Average = (10+11+12+56+66) / 5 = 31
But the formula used by Orion (with reference to SWQL columns) is:
The typical average calculation is to sum up all the values within the filtered period and divide it by the number of data points used to sum.
e.g.
10, 11, 12, 56, 66
Average = (10+11+12+56+66) / 5 = 31
But the formula used by Orion (with reference to SWQL columns) is:
SUM(ResponseTimeHistory.Availability * ResponseTimeHistory.Weight) / SUM(ResponseTimeHistory.Weight) AS [Availability]