---
type: Monitoring Guide
title: "SNMP Disk Space Monitoring: Free-Space Alerts How-To"
description: "Use hrStorageTable to compute free space and set low-disk alerts."
resource: "https://snmp-monitoring.info/monitoring/server/disk-space/"
tags: [monitoring]
timestamp: 2026-07-10T00:00:00Z
---

# SNMP Disk Space Monitoring: Free-Space Alerts How-To

Use hrStorageTable to compute free space and set low-disk alerts.

## Related concepts

- Up: [SNMP Server Monitoring: CPU, RAM, Disk & Uptime](/monitoring/server/index.md)

## Frequently asked questions

### What OID is disk usage in SNMP?

hrStorageUsed at 1.3.6.1.2.1.25.2.3.1.6 for the chosen index (with size .5 and units .4). See sensors/disk.

### How do I get a free-disk-space alert?

Compute free % or free GB from size/used/units, alert when free drops below threshold for multiple polls. Wire notifications in your NMS (alerts).

### How do I convert hrStorage values to GB?

Multiply size or free units by hrStorageAllocationUnits to get bytes, then divide by 1024³ (or 10^9—be consistent).

### Which storage row is my disk?

Match hrStorageDescr to the mount path (and prefer fixed-disk type). Don't assume index numbers.

## Source

Concept generated from https://snmp-monitoring.info/monitoring/server/disk-space/ — the SNMP Monitoring vendor-neutral knowledge base. Content is limited to what that page states (no external claims added here).