Windows Partition Shrink Prep

Commands to run before shrinking a Windows partition via Disk Management or GParted. Windows parks unmovable files (page file, hibernate, VSS snapshots, BitLocker metadata) mid-disk and blocks the shrink — these clear the blockers.

Run all in an admin PowerShell.

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1 — Disable Hibernation

Not needed on VMs. Removes hiberfil.sys.

powercfg /h off

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2 — Disable System Restore & clear VSS snapshots

Disable-ComputerRestore -Drive "C:\"
vssadmin delete shadows /all /quiet

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3 — Disable the Page File

Must reboot after this one.

• Search → “Adjust the appearance and performance of Windows”
• Advanced → Virtual Memory → Change
• Uncheck “Automatically manage” → select C: → No paging file → Set → OK → Reboot

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4 — Disable BitLocker (if enabled)

BitLocker encrypts the whole partition — nothing can move files until it’s off. This is the most common reason the above steps still don’t work.

# Start decryption
Disable-BitLocker -MountPoint "C:"
 
# Check progress
Get-BitLockerVolume -MountPoint "C:" | Select-Object VolumeStatus, EncryptionPercentage

Wait for FullyDecrypted before attempting the shrink. Can take 20-40 mins depending on drive size.

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After Shrinking

Re-enable what you actually want back:

# Re-enable page file — set back to "Automatically manage" in the same UI
# Re-enable System Restore if needed
Enable-ComputerRestore -Drive "C:\"
# Hibernation — only if needed (not on VMs)
powercfg /h on

Leave BitLocker off on VM templates — the Proxmox host controls disk access.