FSLShrinker – FSLogix Profile Container VHDX Shrinker

A PowerShell script that shrinks FSLogix VHDX profile containers to reclaim unused disk space.

Requirements

• Windows Server or Windows 10/11 with administrative privileges
• PowerShell 5.1 or PowerShell 7+
• The defragsvc (Disk Defragmenter) and vds (Virtual Disk Service) services must be startable
• VHDX files must not be in active use by FSLogix when the script runs

Optional: VHDX Filesystem Health Check and Repair

• Administrative privileges are required for Repair-Volume
• No additional modules beyond standard Windows Storage cmdlets are needed; there is no Hyper-V dependency
• No drive letters are assigned or removed. The health check integrates into the script's existing VHDX attach/detach lifecycle. Volumes are resolved from the already-mounted disk by internal object identity (ObjectId), never through a drive letter. This avoids any disruption to FSLogix sessions.
• Important scope: -CheckVhdHealth and -RepairVhd validate and repair the filesystem inside the VHDX container using Repair-Volume. This does not inspect or repair VHDX container metadata or format-level corruption. If a VHDX cannot be mounted at all, that is reported as a container access failure and the disk is skipped.

Configuration

Edit the top of the script to match your environment:

$VHDXLocations = @("F:\Public\User\*\CsProfiles.VHDX", "D:\Public\User\*\CsProfiles.VHDX")
$LogPath = ".\FSLogix-Shrinking-Logs"

• $VHDXLocations – Wildcard paths to your FSLogix profile VHDX files.
• $LogPath – Directory for transcript and CSV log output.

Usage

Run the script directly (it calls Start-DiskShrinker at the bottom), or import and call the function manually.

Basic shrink (default behavior)

.\FSLogix-Profildatenträger\ shrinken.ps1

Or invoke the function explicitly:

Start-DiskShrinker -Path "D:\Public\User\*"

Shrink with VHDX filesystem health check (no repair)

Use -CheckVhdHealth to non-destructively scan each VHDX's filesystem and report healthy/unhealthy status. The check integrates into the existing shrink mount lifecycle — no drive letter is assigned; volumes are identified by internal ObjectId. No modifications are ever made. Issues produce a warning but processing continues for other containers.

Start-DiskShrinker -Path "D:\Public\User\*" -CheckVhdHealth

Shrink with VHDX filesystem health check and repair

Use -RepairVhd to opt into automatic filesystem repair of any VHDX that fails the health check. -RepairVhd implies the health check; you do not need to pass -CheckVhdHealth as well. Repair runs inside the existing mount lifecycle using Repair-Volume -OfflineScanAndFix by ObjectId — no drive letter is ever assigned. The VHDX must not be in active use during repair — ensure all user sessions are logged off.

Start-DiskShrinker -Path "D:\Public\User\*" -RepairVhd

To enable repair in the default bottom-of-script invocation, edit the last Start-DiskShrinker call:

$VHDXLocations | ? {gci $_ -EA 0} | Start-DiskShrinker -LogFilePath "$((gi $LogPath).FullName)\Log.csv" -Verbose -RepairVhd

Parameters

Parameter	Type	Default	Description
-Path	String	(Mandatory)	Wildcard path to VHDX files
-IgnoreLessThanGB	Double	0	Skip disks smaller than this size
-DeleteOlderThanDays	Int	—	Delete disks not accessed for this many days
-RollingLog	Switch	$false	Append timestamp to log filename
-LogFilePath	String	%TEMP%\FslShrinkDisk …csv	Path for the CSV results log
-PassThru	Switch	$false	Output result objects to the pipeline
-ThrottleLimit	Int	4	Maximum parallel threads
-RatioFreeSpace	Double	0.05	Minimum free-space ratio to trigger shrink
-CheckVhdHealth	Switch	$false	Non-destructively scan the filesystem inside each VHDX using its already-mounted volume; report status, never modify. No drive letter is assigned.
-RepairVhd	Switch	$false	Check health then repair the filesystem inside unhealthy VHDXs using Repair-Volume -OfflineScanAndFix by ObjectId; implies the health check. No drive letter is assigned.

VHDX Filesystem Check and Repair – Behavior and Caveats

• -CheckVhdHealth is read-only: it runs Repair-Volume -Scan on the already-mounted volume using its internal ObjectId (no drive letter), reports the result, and never alters any file.
• -RepairVhd implies the health check: it scans first and runs Repair-Volume -OfflineScanAndFix only for VHDXs that have filesystem errors. You do not need to pass both switches.
• Neither switch is active by default. Normal runs are unaffected.
• No drive letters are assigned or removed. The health check and repair both operate on the volume that is already mounted by the shrink workflow. Volumes are located by ObjectId, not a drive letter. This avoids disrupting FSLogix sessions.
• No Hyper-V dependency. Only standard Windows Storage cmdlets (Repair-Volume) are used.
• Filesystem-vs-container scope: These switches check and repair the NTFS/ReFS filesystem hosted inside the VHDX. They do not inspect or repair VHDX container metadata corruption. If a VHDX cannot be mounted, the failure is reported as a container access error and that disk is skipped.
• The VHDX must not be in active use during repair. Ensure the user's FSLogix session is logged off and the container is not mounted before running with -RepairVhd.
• If Repair-Volume fails for a specific container, an error is recorded for that file but other containers continue unaffected.
• After repair, normal shrinking proceeds. If the repair did not fully fix the container, subsequent operations may still fail and will be logged accordingly.

Logging

• Transcript: $LogPath\Output.txt
• CSV results: $LogPath\Log.csv (one row per processed VHDX)

License

See repository for license details.