Windows – File History keeps saving copies of files that haven’t changed

Or, you can use the old Backup that's actually still inside Windows 8

Although there's no guarantee it will still work on later version (9?).

Unfortunately the API is not very straightforward to use - most of the relevant calls are to a COM object that doesn't implement IDispatch. It would therefore be exceedingly difficult and messy to call these functions from PowerShell. These are the calls we need to make:

• CoCreateInstance to get the FhConfigMgr object
• IFhConfigMgr::CreateDefaultConfiguration to create the configuration or replace an old one
• IFhConfigMgr::ProvisionAndSetNewTarget to set the backup target folder
• IFhConfigMgr::SetLocalPolicy to set the policy to only delete when space is needed
• IFhConfigMgr::SetBackupStatus to turn on File History
• IFhConfigMgr::SaveConfiguration to commit the changes
• FhServiceOpenPipe to get a handle to the File History service
• FhServiceReloadConfiguration to tell the service to reload its settings
• FhServiceClosePipe to close the handle to the service

To call all these functions, we can use my open-source application SprintDLL. I wrote this script for you, commented with faux-C++ equivalents of each section:

// CoCreateInstance(CLSID_FhConfigMgr, NULL, CLSCTX_INPROC_SERVER, IID_IFhConfigMgr, &fh)
newslot native fhPtr
call ole32.dll!CoCreateInstance /return uint (blockptr(guid {ED43BB3C-09E9-498a-9DF6-2177244C6DB4}), nullptr, int 1, blockptr(guid {6A5FEA5B-BF8F-4EE5-B8C3-44D8A0D7331C}), slotptr fhPtr)
newslot native fh
copyslot fh = fhPtr dereferenced
newslot block vtbl = nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr
copyslot vtbl = fh dereferenced

// fh->CreateDefaultConfiguration(TRUE)
newslot native createDefaultConfiguration
copyslot createDefaultConfiguration = vtbl field 4
call funcat createDefaultConfiguration /call thiscall /return uint (slotdata fhPtr, int 1)

// fh->ProvisionAndSetNewTarget("\\localhost\FileHistory$\", "Local Disk")
newslot native provisionAndSetNewTarget
copyslot provisionAndSetNewTarget = vtbl field 14
call funcat provisionAndSetNewTarget /call thiscall /return uint (slotdata fhPtr, bstr "\\\\localhost\\FileHistory$\\", bstr "Local Disk")

// fh->SetLocalPolicy(FH_RETENTION_TYPE, FH_RETENTION_UNLIMITED)
newslot native setLocalPolicy
copyslot setLocalPolicy = vtbl field 9
call funcat setLocalPolicy /call thiscall /return uint (slotdata fhPtr, int 1, int 1)

// fh->SetBackupStatus(FH_STATUS_ENABLED)
newslot native setBackupStatus
copyslot setBackupStatus = vtbl field 11
call funcat setBackupStatus /call thiscall /return uint (slotdata fhPtr, int 2)

// fh->SaveConfiguration()
newslot native saveConfiguration
copyslot saveConfiguration = vtbl field 5
call funcat saveConfiguration /call thiscall /return uint (slotdata fhPtr)

// FhServiceOpenPipe(TRUE, &fhPipe)
newslot native fhPipe
call fhsvcctl.dll!FhServiceOpenPipe /return int (int 1, slotptr fhPipe)

// FhServiceReloadConfiguration(fhPipe)
call fhsvcctl.dll!FhServiceReloadConfiguration /return int (slotdata fhPipe)

// FhServiceClosePipe(fhPipe)
call fhsvcctl.dll!FhServiceClosePipe /return int (slotdata fhPipe)

I got the VTable field IDs from the positions of the functions in the C-style COM interface for the File History manager COM object. If the script succeeds, it will say that every function returned zero.

To use the script, save it to a file, e.g. filehistory.sprint. You can then run it from a batch file like this:

sprintdll run filehistory.sprint

If deploying across the network, you might want to include a command that copies the utility and the script onto the local machine first.