Applications Systems

How the SolarWinds Platform calculates volume metrics on a SNMP monitored node

Volume data is showing incorrect on SNMP polled nodes. Volume data is incorrect. How to troubleshoot volumes that are polling incorrect volume data. This article describes how the SolarWinds Platform searches and calculates volume information in SAM & NPM. This applies to any device that uses SNMP type polling. Volume metrics are calculated using the methods described below.

First published date

10/17/2018 3:22 PM

Last published date

3/5/2025 4:37 PM

Overview

This article provides information on how the SolarWinds Platform searches and calculates volume information in SAM and NPM products. This article should be used for determining the root cause of volume metrics that are considered incorrect or inaccurate. Anytime when volume data is showing more used space than total space, incorrect usage of the current volume, incorrect total volume size, etc.

Product section

Server Application Monitor

Cause

SNMP daemon is returning incorrect volume metrics.

Resolution

Obtain an SNMP walk from the device to gather the latest metrics the device is reporting for volumes. 
Run SolarWinds SNMP Walk

Search the text file for the OID's below. There will be multiple entries if there are multiple volumes mounted on the device. Ensure that you select the metrics from the correct volume. 
 

OID Information
OID NameOID Value
AllocationUnits.1.3.6.1.2.1.25.2.3.1.4
TotalSize.1.3.6.1.2.1.25.2.3.1.5
UsedSize.1.3.6.1.2.1.25.2.3.1.6

 

Based on the above, you can use the following formulas.

Total Size Formula:

TotalSizeOID * AllocationUnitsOID = Total Size in Bytes

Used Size Formula:

UsedSizeOID * AllocationUnitsOID = Used Size in Bytes

Available Size Formula:

Total Size in Bytes - Used Size in Bytes

 

EX: If I have the following OIDs and resulting values, I can obtain the total, used, and available space on that particular volume

AllocationUnits --    .1.3.6.1.2.1.25.2.3.1.4.31 = INTEGER: 4096
TotalSize --        .1.3.6.1.2.1.25.2.3.1.5.31 = INTEGER: 9694070
UsedSize --        .1.3.6.1.2.1.25.2.3.1.6.31 = INTEGER: 3212850

 

Total Size Calculation:
Formula:    TotalSizeOID * AllocationUnitsOID / 1024 / 1024 / 1024 = Total Size
Example:    9694070 * 4096 / 1024 / 1024 / 1024 = 36.9GB Total Size

Used Space Calculation:
Formula:     UsedSizeOID * AllocationUnitsOID / 1024 / 1024 / 1024 = Used Size
Example:    3212850 * 4096 / 1024 / 1024 / 1024 = 12.26GB Used Size

Available Calculation:

36.9GB - 12.26GB = 24.64GB Available


Note: If the information calculated from your SNMP data is incorrect, the options are:
 • Install a Linux Agent if your device is a supported distribution and collect volume metrics through the agent. 
 • Contact the device vendor and troubleshoot the SNMP metrics with their support team.
 • Use the Poller Checker tool to attempt new pollers. This is not recommended as a permanent fix.
 • Contact SolarWinds Support for questions on this article, how to troubleshoot your volume metrics, or have questions on the alternative options.