Network Management

Advanced Options for Changing Memory Usage Calculation on Linux Agent Nodes

This article explains how system administrators can customize the calculation of memory usage on Linux servers monitored by SolarWinds Platform Agent nodes to more accurately reflect Used and Free memory metrics.

First published date

10/21/2025 12:00 PM

Last published date

10/21/2025 12:00 PM

Overview

In SolarWinds Platform 2025.4, a new Advanced Configuration setting called LinuxFreeMemoryStrategyList was introduced. This setting allows you to define the priority order of strategies used to calculate unused (free) memory on Linux servers. This directly impacts the reported overall memory utilization. 

 

Memory Calculation Strategies

  1. cache (default)
    • Formula:
      Memory Used = MemTotal - MemFree - Buffers - Cached
    • This method treats cached and buffered memory as free.
  2. available
    • Formula:
      Memory Used = MemTotal - MemAvailable
    • MemAvailable is a kernel metric available since Linux kernel version 3.14 (approximately 2014, CentOS 7).
  3. cachesrec
    • Formula:
      Memory Used = MemTotal - MemFree - Buffers - Cached - SReclaimable
    • SReclaimable is available since Linux kernel version 2.6.19 (CentOS 6).
  4. free
    • Formula:
      Memory Used = MemTotal - MemFree
    • This is the simplest calculation, considering only free memory.

Product section

Orion Platform

Resolution

Setting Syntax and Usage

  • The LinuxFreeMemoryStrategyList setting allows you to specify a prioritized list of these strategies separated by the > character.
  • The first supported strategy in the list (based on the Linux distribution and kernel version) will be used for memory calculation.
  • The default value is an empty string, which SolarWinds interprets as:
    cache > available > cachesrec > free
  • To prioritize using the MemAvailable metric (recommended for Linux kernels 3.14 and newer) with fallback to other methods, set:
    available > cache > cachesrec > free

Impacted Features

This setting affects memory usage calculation for the Node memory poller, which provides data displayed in the following widgets:
  • CPU Load & Memory Usage – Real Time Data
  • CPU Load & Memory Utilization

 

  • Some Linux nodes also report memory utilization via a dedicated Physical Memory volume.