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Home > Success Center > Network Performance Monitor (NPM) > Availability report differences between web-based and Report Writer

Availability report differences between web-based and Report Writer

Table of contents

Updated July 17, 2017

Overview

This article describes the reporting discrepancies between Report Writer and web-based reports. 

Environment

All NPM versions

Detail

The value of the report data changes every month because of the daily maintenance that runs every night. From the Orion database, there are three historical tables that contain ResponseTime data: Detail, Hourly and Daily. The daily maintenance summarizes data that are older than seven days from the Detail table to an Hourly table, and then data older than 30 days from the Hourly table to a Daily table. During summarization, data for minimum, maximum and average value are calculated from several rows into one and this is why the AVG value changes in the resource.

For example:

A ResponseTime Detail table contains the following information:

2017-07-11 00:10:00 100
2017-07-11 00:00:00 60
2017-07-10 23:50:00 70
2017-07-10 23:40:00 100

A ResponseTime Hourly table contains the following information:

2017-07-09 3:00:00 100 
2017-07-09 2:00:00 100
2017-07-09 1:00:00 100 
2017-07-09 0:00:00 100

The AVG is calculated as 100+60+70+100+100+100+100+100)/8 = 91.25

The daily maintenance moves the data for 2017-07-10 to an Hourly table.

The Detail table contains the following information:
2017-07-11 00:10:00 100
2017-07-11 00:00:00 60

The Hourly table contains the following information:

2017-07-10 23:00:00 85 summarized (70+100)/2
2017-07-09 3:00:00 100 
2017-07-09 2:00:00 100
2017-07-09 1:00:00 100 
2017-07-09 0:00:00 100

The AVG is calculated as 100+60+85+100+100+100+100)/7 = ~ 92.142. The results are in the same period but the AVG values are different because of the previous maintenance summarization.

 

The same behavior is also observed on web-based reporting. The value changes for last month's availability the same way that it changes on the resource. This behavior is by design and worked in the previous product versions. You can also update the retention intervals by setting the Detailed Statistics Retention to 61 days to keep the data in the Detail table with no summarization needed. The hourly retention can be updated to 90 days. This guarantees that the AVG availability will be static for the current month and previous month but not the whole year.

 

Note: Increasing retention intervals can lead to database size growth and can result in some performance penalties. Alternatively, you can contact SolarWinds Support and request them to send a ticket to our Development team as a Feature Request regarding availability statistics calculation.

 

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