Feature addition - only if your interested just close this issue off if your not.

[damobeanrod]

G'day,
Love your work.
Not sure how to contribute new to GitHub - yes I'll google it late haha

I have expanded on your nice work.
it uses sdelete to zero the blocks
then defrags
then compacts.

In my case runaway print cache folder I found your script useful on a 6GB UPD as an example
I removed a 4GB folder compact alone was 100MB saved
sdelete gave me about 400MB
sdelete plus defrag gave me about 4GB back ....

Below is what I ended up with.

$VHDXPaths = @(
'D:\CMVTBDealerPRO'
)

$VHDXExclusions = @(
'UVHD-template.vhdx'
)

Foreach ($Path in $VHDXPaths){
$AllUPDs = Get-ChildItem $Path -Recurse -Filter *.vhdx | Where-Object {$VHDXExclusions -NotContains $_.name} | Select-Object -ExpandProperty fullname

foreach ($UPD in $AllUPDs){
    New-Item -Name compact.txt -ItemType file -force | OUT-NULL
    ADD-CONTENT -Path compact.txt "select vdisk file= $UPD"
    ADD-CONTENT -Path compact.txt "attach vdisk"
    DISKPART /S compact.TXT
    .\sdelete64.exe -z E:\
    Start-Sleep -s 3
    defrag E:
    New-Item -Name compact.txt -ItemType file -force | OUT-NULL
    ADD-CONTENT -Path compact.txt "select vdisk file= $UPD"
    ADD-CONTENT -Path compact.txt "detach vdisk"
    DISKPART /S compact.TXT
    NEW-ITEM -Name compact.txt -ItemType file -force | OUT-NULL
    ADD-CONTENT -Path compact.txt "select vdisk file= $UPD"
    ADD-CONTENT -Path compact.txt "compact vdisk"
    DISKPART /S compact.TXT
}

}