PowerShell: Setting Windows Pagefile

# setPageFile.ps1
# Source: 
# Reposting here as such code seems to be open source and the remote server may disappear from the web due to its non-SSL compliance.

Function Set-PageFile {
<#
.SYNOPSIS
Set-PageFile is an advanced function which can be used to adjust virtual memory page file size.
.DESCRIPTION
Set-PageFile is an advanced function which can be used to adjust virtual memory page file size.
.PARAMETER <InitialSize>
Setting the paging file's initial size.
.PARAMETER <MaximumSize>
Setting the paging file's maximum size.
.PARAMETER <DriveLetter>
Specifies the drive letter you want to configure.
.PARAMETER <SystemManagedSize>
Allow Windows to manage page files on this computer.
.PARAMETER <None>
Disable page files setting.
.PARAMETER <Reboot>
Reboot the computer so that configuration changes take effect.
.PARAMETER <AutoConfigure>
Automatically configure the initial size and maximumsize.
.EXAMPLE
C:\PS> Set-PageFile -InitialSize 1024 -MaximumSize 2048 -DriveLetter "C:","D:"

Execution Results: Set page file size on "C:" successful.
Execution Results: Set page file size on "D:" successful.

Name InitialSize(MB) MaximumSize(MB)
---- --------------- ---------------
C:\pagefile.sys 1024 2048
D:\pagefile.sys 1024 2048
E:\pagefile.sys 2048 2048
.LINK
Get-WmiObject
https://learn.microsoft.com/en-us/powershell/module/microsoft.powershell.management/get-wmiobject?view=powershell-5.1
#>
[cmdletbinding(SupportsShouldProcess,DefaultParameterSetName="SetPageFileSize")]
Param
(
[Parameter(Mandatory,ParameterSetName="SetPageFileSize")]
[Alias('is')]
[Int32]$InitialSize,

[Parameter(Mandatory,ParameterSetName="SetPageFileSize")]
[Alias('ms')]
[Int32]$MaximumSize,

[Parameter(Mandatory)]
[Alias('dl')]
[ValidatePattern('^[A-Z]$')]
[String[]]$DriveLetter,

[Parameter(Mandatory,ParameterSetName="None")]
[Switch]$None,

[Parameter(Mandatory,ParameterSetName="SystemManagedSize")]
[Switch]$SystemManagedSize,

[Parameter()]
[Switch]$Reboot,

[Parameter(Mandatory,ParameterSetName="AutoConfigure")]
[Alias('auto')]
[Switch]$AutoConfigure
)
Begin {}
Process {
If($PSCmdlet.ShouldProcess("Setting the virtual memory page file size")) {
$DriveLetter | ForEach-Object -Process {
$DL = $_
$PageFile = $Vol = $null
try {
$Vol = Get-CimInstance -ClassName CIM_StorageVolume -Filter "Name='$($DL):\\'" -ErrorAction Stop
} catch {
Write-Warning -Message "Failed to find the DriveLetter $DL specified"
return
}
if ($Vol.DriveType -ne 3) {
Write-Warning -Message "The selected drive should be a fixed local volume"
return
}
Switch ($PsCmdlet.ParameterSetName) {
None {
try {
$PageFile = Get-CimInstance -Query "Select * From Win32_PageFileSetting Where Name='$($DL):\\pagefile.sys'" -ErrorAction Stop
} catch {
Write-Warning -Message "Failed to query the Win32_PageFileSetting class because $($_.Exception.Message)"
}
If($PageFile) {
try {
$PageFile | Remove-CimInstance -ErrorAction Stop
} catch {
Write-Warning -Message "Failed to delete pagefile the Win32_PageFileSetting class because $($_.Exception.Message)"
}
} Else {
Write-Warning "$DL is already set None!"
}
break
}
SystemManagedSize {
Set-PageFileSize -DL $DL -InitialSize 0 -MaximumSize 0
break
}
AutoConfigure {
$TotalPhysicalMemorySize = @()
#Getting total physical memory size
try {
Get-CimInstance Win32_PhysicalMemory -ErrorAction Stop | ? DeviceLocator -ne "SYSTEM ROM" | ForEach-Object {
$TotalPhysicalMemorySize += [Double]($_.Capacity)/1GB
}
} catch {
Write-Warning -Message "Failed to query the Win32_PhysicalMemory class because $($_.Exception.Message)"
}
<#
By default, the minimum size on a 32-bit (x86) system is 1.5 times the amount of physical RAM if physical RAM is less than 1 GB,
and equal to the amount of physical RAM plus 300 MB if 1 GB or more is installed. The default maximum size is three times the amount of RAM,
regardless of how much physical RAM is installed.
If($TotalPhysicalMemorySize -lt 1) {
$InitialSize = 1.5*1024
$MaximumSize = 1024*3
Set-PageFileSize -DL $DL -InitialSize $InitialSize -MaximumSize $MaximumSize
} Else {
$InitialSize = 1024+300
$MaximumSize = 1024*3
Set-PageFileSize -DL $DL -InitialSize $InitialSize -MaximumSize $MaximumSize
}
#>


$InitialSize = (Get-CimInstance -ClassName Win32_PageFileUsage).AllocatedBaseSize
$sum = $null
(Get-Counter '\Process(*)\Page File Bytes Peak' -SampleInterval 15 -ErrorAction SilentlyContinue).CounterSamples.CookedValue | % {$sum += $_}
$MaximumSize = ($sum*70/100)/1MB
if ($Vol.FreeSpace -gt $MaximumSize) {
Set-PageFileSize -DL $DL -InitialSize $InitialSize -MaximumSize $MaximumSize
} else {
Write-Warning -Message "Maximum size of page file being set exceeds the freespace available on the drive"
}
break

}
Default {
if ($Vol.FreeSpace -gt $MaximumSize) {
Set-PageFileSize -DL $DL -InitialSize $InitialSize -MaximumSize $MaximumSize
} else {
Write-Warning -Message "Maximum size of page file being set exceeds the freespace available on the drive"
}
}
}
}

# Get current page file size information
try {
Get-CimInstance -ClassName Win32_PageFileSetting -ErrorAction Stop |Select-Object Name,
@{Name="InitialSize(MB)";Expression={if($_.InitialSize -eq 0){"System Managed"}else{$_.InitialSize}}},
@{Name="MaximumSize(MB)";Expression={if($_.MaximumSize -eq 0){"System Managed"}else{$_.MaximumSize}}}|
Format-Table -AutoSize
} catch {
Write-Warning -Message "Failed to query Win32_PageFileSetting class because $($_.Exception.Message)"
}
If($Reboot) {
Restart-Computer -ComputerName $Env:COMPUTERNAME -Force
}
}
}
End {}
}

Function Set-PageFileSize {
[CmdletBinding()]
Param(
[Parameter(Mandatory)]
[Alias('dl')]
[ValidatePattern('^[A-Z]$')]
[String]$DriveLetter,

[Parameter(Mandatory)]
[ValidateRange(0,[int32]::MaxValue)]
[Int32]$InitialSize,

[Parameter(Mandatory)]
[ValidateRange(0,[int32]::MaxValue)]
[Int32]$MaximumSize
)
Begin {}
Process {
#The AutomaticManagedPagefile property determines whether the system managed pagefile is enabled.
#This capability is not available on windows server 2003,XP and lower versions.
#Only if it is NOT managed by the system and will also allow you to change these.
try {
$Sys = Get-CimInstance -ClassName Win32_ComputerSystem -ErrorAction Stop
} catch {

}

If($Sys.AutomaticManagedPagefile) {
try {
$Sys | Set-CimInstance -Property @{ AutomaticManagedPageFile = $false } -ErrorAction Stop
Write-Verbose -Message "Set the AutomaticManagedPageFile to false"
} catch {
Write-Warning -Message "Failed to set the AutomaticManagedPageFile property to false in Win32_ComputerSystem class because $($_.Exception.Message)"
}
}

# Configuring the page file size
try {
$PageFile = Get-CimInstance -ClassName Win32_PageFileSetting -Filter "SettingID='pagefile.sys @ $($DriveLetter):'" -ErrorAction Stop
} catch {
Write-Warning -Message "Failed to query Win32_PageFileSetting class because $($_.Exception.Message)"
}

If($PageFile){
try {
$PageFile | Remove-CimInstance -ErrorAction Stop
} catch {
Write-Warning -Message "Failed to delete pagefile the Win32_PageFileSetting class because $($_.Exception.Message)"
}
}
try {
New-CimInstance -ClassName Win32_PageFileSetting -Property @{Name= "$($DriveLetter):\pagefile.sys"} -ErrorAction Stop | Out-Null

# https://learn.microsoft.com/en-us/windows/win32/cimwin32prov/win32-pagefilesetting?redirectedfrom=MSDN
Get-CimInstance -ClassName Win32_PageFileSetting -Filter "SettingID='pagefile.sys @ $($DriveLetter):'" -ErrorAction Stop | Set-CimInstance -Property @{
InitialSize = $InitialSize ;
MaximumSize = $MaximumSize ;
} -ErrorAction Stop

Write-Verbose -Message "Successfully configured the pagefile on drive letter $DriveLetter"

} catch {
Write-Warning "Pagefile configuration changed on computer '$Env:COMPUTERNAME'. The computer must be restarted for the changes to take effect."
}
}
End {}
}

Function viewPageFiles{
 return (Get-CimInstance -ComputerName $name -Class Win32_PageFileUsage|%{"$($_.Name) Allocated: $($_.AllocatedBaseSize) MB CurrentUsage: $($_.CurrentUsage) MB PeakUsage: $($_.PeakUsage) MB"}|out-string).Trim()
}


# Usage:
viewPageFiles
Set-PageFile -InitialSize 100mb -MaximumSize 16GB -DriveLetter "B:"