How to Clean Up IIS Log Files on Windows Server

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Over time, log files can take up a lot of disk space, and it is essential to clear them periodically to avoid disk space issues. In this blog post, we will explain how to remove IIS log files on a Windows Server.

Find the IIS Log Files Location

Before you can delete the IIS log files, you must first find out their location. Since Windows Server 2008, the default location for the IIS log files has been in %SystemDrive%\inetpub\logs\LogFiles\W3SVC<ID> where %id is the ID number of the site.

For example, the first website log files are located in %SystemDrive%\inetpub\logs\LogFiles\W3SVC1, while the second website log files are in %SystemDrive%\inetpub\logs\LogFiles\W3SVC2, and so on.

Of course, that’s assuming that you have not customized or moved the IIS log files path. So how do we confirm the IIS log files’ location?

Using the IIS Manager

On the IIS server, press CTRL+R to open the Run dialog, type inetmgr, and press Enter or click OK.

Navigate to SERVER > Sites > Website, and double-click the Logging feature.

The logs path is shown on the Directory box, similar to the image below.

If you have more than one IIS website, repeat the same steps to find the log path for the other websites.

As you can see below, this IIS website has 31 log files with sizes ranging between 100 MB and 150 MB. If left unmanaged, the IIS log files will continue growing, leading to disk space depletion.

Using PowerShell

Manually checking each website’s IIS log file path in the GUI is fine if you have a small number of sites. But what if you have multiple sites? Clicking through the IIS Manager can take time and effort. So instead, let’s use PowerShell to list each website’s IIS log files location.

# Get IIS Site Log Files Path 
Import-Module WebAdministration 
Get-Website | ForEach-Object { 
New-Object psobject -Property $( 
[ordered]@{ 
Site = $_.Name; 
LogPath = $(($_.LogFile.Directory).ToString().Replace('%SystemDrive%', $env:SystemDrive)) + "\W3SVC$($_.id)\" 
} 
) 
}

This PowerShell code retrieves a list of websites using the Get-Website cmdlet from the WebAdministration module. For each website, it creates a new PowerShell object with two properties: Site and LogPath.

The Site property contains the website name, while the LogPath property contains the path to the website’s log file directory based on the website’s ID.

You could save this script as Get-SiteLogPath.ps1 and run it like so:

.\Get-SiteLogPath

Delete IIS Log Files

Deleting all IIS log files is not recommended. You should consider retaining the log files from at least the last 3 to 7 days. This way, you still have the log files to review should you need them.

Delete the IIS files using the File Explorer

Like any file on the system, you can delete the IIS files from File Explorer. Once you locate the folder, select the files and delete them. You can press Shift+Delete to delete the files permanently without going to the Recycle Bin.

Repeat the same steps if you have more than one website.

Delete the IIS files using a PowerShell Script

While deleting files from the File Explorer is okay for one-off housekeeping or a few sites, automating this task using PowerShell is preferable, especially when there are multiple sites and large IIS logs to remove.

Copy the script below and save it as Delete-IISLogs.ps1.

[CmdletBinding()]
param (
[Parameter()]
[int]
$OlderThanXDays = 7,

[Parameter()]
[switch]
$WhatIf
)

# Get IIS Site Log Files Path
Import-Module WebAdministration

## Get the IIS logs folder of all websites.
$iis_log_folders = @(
Get-Website | ForEach-Object {
[PSCustomObject]@{
Site = $_.Name
LogPath = $(($_.LogFile.Directory).ToString().Replace('%SystemDrive%', $env:SystemDrive)) + "\W3SVC$($_.Id)"
}
}
)

## Delete the IIS log files older than $OlderThanXDays
$thresholdDate = (Get-Date).AddDays(-$OlderThanXDays)

# Store deleted file information
$DeletedFiles = @()

# Create log folder if it doesn't exist
$LogFolder = "C:\Logs"

if (!(Test-Path $LogFolder)) {
New-Item `
-Path $LogFolder `
-ItemType Directory `
-Force | Out-Null
}

$iis_log_folders.LogPath | ForEach-Object {

if (Test-Path $_) {

Get-ChildItem -Path $_ -Filter *.log |
Where-Object { $_.LastWriteTime -lt $thresholdDate } |
ForEach-Object {

try {

Remove-Item `
-Path $_.FullName `
-Confirm:$false `
-Force `
-ErrorAction Stop `
-Verbose `
-WhatIf:$WhatIf

$DeletedFiles += [PSCustomObject]@{
FileName = $_.Name
FullPath = $_.FullName
SizeMB = [math]::Round($_.Length / 1MB, 2)
Action = if ($WhatIf) { "Preview" } else { "Deleted" }
DeletedOn = Get-Date
}

}
catch {

$DeletedFiles += [PSCustomObject]@{
FileName = $_.Name
FullPath = $_.FullName
SizeMB = [math]::Round($_.Length / 1MB, 2)
Action = "Failed"
DeletedOn = Get-Date
}

Write-Warning "Failed to delete file: $($_.FullName)"
}
}
}
else {
Write-Warning "Log folder not found: $_"
}
}

# Export deletion log
$DeletedFiles |
Export-Csv `
-Path "C:\Logs\IISLogCleanup.csv" `
-NoTypeInformation

# Display summary
$TotalFiles = $DeletedFiles.Count

$TotalSizeMB = [math]::Round(
($DeletedFiles | Measure-Object SizeMB -Sum).Sum,
2
)

Write-Host "Processed files: $TotalFiles"
Write-Host "Total size: $TotalSizeMB MB"
Write-Host "Log saved to C:\Logs\IISLogCleanup.csv"

Note that when the -WhatIf switch is used, no files are actually removed. The generated CSV log marks these entries as Preview so you can review which files would be deleted before running the script for real.

The script mentioned above checks whether each IIS log directory exists before attempting to delete files. This helps prevent errors if a website has been removed/its log directory is no longer available.

This script accepts one parameter called OlderThanXDays, which specifies the starting age of the IIS log file to delete. For example, run the following command to delete the IIS log files older than 7 days.

.\Delete-IISLogs.ps1 -OlderThanXDays 7

In order to preview which IIS log files would be deleted without actually removing them, run the following command:

.\Delete-IISLogs.ps1 `
-OlderThanXDays 7 `
-WhatIf

You can now confirm that the script deleted the IIS log files older than 7 days.

The script mentioned above also records info about deleted files and exports the results to a CSV file. You can use this log for auditing purposes (it includes the file name, full path, size, and deletion timestamp).

Create a Scheduled Task to Delete IIS Log Files

Now that you have a working script, let’s create a scheduled task so that it runs unattended at a specific interval.

This code registers a new scheduled task with the following details.

• Task name: Delete IIS Logs Older Than 7 Days.
• Description: Delete IIS Logs Older Than 7 Days.
• Action: Run the Delete-IISLogs.ps1 script with the -OlderThanXDays 7 parameter.
• Trigger: Every Sunday at 1AM.
• Task principal (user): The local SYSTEM account.
• Run level: With the highest privileges.
• Compatibility: The highest version available is always represented by the Win8 value.

# Register the scheduled task 
$taskParams = @{ 
TaskName = 'Delete IIS Logs Older Than 7 Days' 
Action = (New-ScheduledTaskAction -Execute 'powershell.exe' -Argument '-ExecutionPolicy Bypass -File C:\scripts\Delete-IISLogs.ps1 -OlderThanXDays 7') 
Trigger = (New-ScheduledTaskTrigger -Weekly -At 1AM -DaysOfWeek Sunday) 
Description = 'Delete IIS Logs Older Than 7 Days' 
User = 'SYSTEM' 
RunLevel = 'Highest' 
Settings = (New-ScheduledTaskSettingsSet -Compatibility Win8) 
} 
Register-ScheduledTask @taskParams

If you use PowerShell 7, you need to replace powershell.exe with pwsh.exe in the scheduled task action.

Now, open the Task Scheduler app and confirm the new scheduled task.

Conclusion

To sum up, clearing IIS log files is a crucial maintenance task for any Windows Server administrator. The build-up of log files can consume valuable storage space and cause other services to fail.

By following the step-by-step guide discussed in this blog post, you can efficiently clear IIS log files on your Windows Server without compromising the functionality of your website. Regular log file cleaning can keep your server operating smoothly and mitigate disk space-related problems.

Now that you better understand how to clear IIS log files, it’s time to take action and implement these techniques on your server. By doing so, you can enhance server performance and improve overall website performance.

So, give it a try, and share your experience with us in the comments section below!