Windows Drive Space Monitoring Using PowerShell Script
Purpose:
To automate disk space monitoring on a Windows server and send email alerts when free space falls below a defined threshold. This helps ensure system stability and prevent outages due to storage issues.
Files and Configuration
Script: DiskSpaceMonitor.ps1
This script checks all fixed drives (DriveType = 3), calculates the free space percentage, and sends an HTML email if any drive falls below a specified threshold.
Key Configurable Parameters:
$smtpServer– SMTP server to relay email (e.g., mail.company.com).$from– Sender email address.$to– Recipient(s) email address.$threshold– Minimum acceptable free space percentage (e.g., 20%).
Ensure this file is saved in a known path, e.g., C:\Monitoring\DiskSpaceMonitor.ps1.
Scripts:-
# DiskSpaceMonitor.ps1
# Configuration
$smtpServer = “*******.****.****”
$from = “*******@****.****”
$to = “*******@****.****”
$cc = “*******@****.****”
$subject = “Disk Space Alert on $env:COMPUTERNAME”
$threshold = 20 # percentage
# Get disk space info
$drives = Get-WmiObject Win32_LogicalDisk -Filter “DriveType = 3″
$alertDrives = @()
foreach ($drive in $drives) {
$freePercent = [math]::Round(($drive.FreeSpace / $drive.Size) * 100, 2)
if ($freePercent -lt $threshold) {
$alertDrives += @{
Drive = $drive.DeviceID
SizeGB = [math]::Round($drive.Size / 1GB, 2)
FreeGB = [math]::Round($drive.FreeSpace / 1GB, 2)
FreePercent = $freePercent
}
}
}
# Build HTML body if any drive is low
if ($alertDrives.Count -gt 0) {
$body = @”
<html>
<head>
<style>
table {border-collapse: collapse; width: 100%;}
th, td {border: 1px solid #ccc; padding: 8px; text-align: left;}
th {background-color: #f2f2f2;}
.low {background-color: #f28b82;} /* Red */
.warn {background-color: #fff3cd;} /* Orange */
</style>
</head>
<body>
<p>Dear Team,</p>
<p><b>Report As On:</b> $(Get-Date -Format “dd MMM yyyy HH:mm”)</p>
<p><b>Warning!</b> Low disk space detected on server <b>$env:COMPUTERNAME</b>:</p>
<table>
<tr><th>Drive</th><th>Total Size (GB)</th><th>Free Space (GB)</th><th>Free Space (%)</th></tr>
“@
foreach ($drive in $alertDrives) {
$rowClass = “”
if ($drive.FreePercent -lt 10) {
$rowClass = “low”
} elseif ($drive.FreePercent -le 20) {
$rowClass = “warn”
}
$body += “<tr class=’$rowClass’><td>$($drive.Drive)</td><td>$($drive.SizeGB)</td><td>$($drive.FreeGB)</td><td>$($drive.FreePercent)%</td></tr>`n”
}
$body += “</table><p>Regards,<br/>Automated Disk Monitor – By DBA Team</p></body></html>”
# Send the email
Send-MailMessage -From $from -To $to -Cc $cc -Subject $subject -Body $body -BodyAsHtml -SmtpServer $smtpServer
}
Prerequisites
-
SMTP Relay Access
-
- Ensure port 25 (SMTP) is open to the SMTP server (
$smtpServer) from this server. - Confirm that the sending address (
$from) is authorized to send through this relay. - Validate DNS resolution and firewall rules for the mail server.
- Ensure port 25 (SMTP) is open to the SMTP server (
-
Execution Policy
-
Run the following in PowerShell (as Administrator) to allow the script to run:
Set-ExecutionPolicy RemoteSigned
-
3.Test Script Manually Before automating, test manually:
Schedule the Script in Task Scheduler
-
Open Task Scheduler
PressWin + R, typetaskschd.msc, and press Enter. -
Create a Basic Task
-
- Name:
Disk Space Monitor - Description: Alerts if disk space is low on the server.
- Name:
-
Trigger
-
- Choose
DailyorRepeat every X hoursdepending on your need.
- Choose
-
Action
-
- Choose
Start a program - Program/script:
- Choose
- Add arguments:
5.Finish and Save
Testing and Logs
- After scheduling, right-click the task and click Run to verify execution.
- Check for emails and review the Task Scheduler History for failures.
- Optionally, add logging inside the script to output to a
.logfile.
Email Output Sample
Dear Team,
Report As On: 01 May 2025 13:12
Warning! Low disk space detected on server SRV01:
Drive | Total Size (GB) | Free Space (GB) | Free Space (%)
C: | 100 | 15 | 15.00
D: | 200 | 25 | 12.50
Regards,
Automated Disk Monitor – By IT Team
Maintenance Tips
- Update recipient list as needed.
- Re-test SMTP if mail stops working (relay or DNS may change).
- Update threshold based on system growth trends.
