Active Directory Cookbook

16.11. Determining How Much Whitespace Is in the DIT

Problem

You want to find the amount of whitespace in your DIT. A lot of whitespace in the DIT may mean that you could regain enough space on the disk to warrant performing an offline defrag.

Solution

Using a graphical user interface

1. Run regedit.exe from the command line or Start → Run.

2. Expand HKEY_LOCAL_MACHINE → SYSTEM → CurrentControlSet → Services → NTDS → Diagnostics.

3. In the right pane, double-click on 6 Garbage Collection.

4. For Value data, enter 1.

5. Click OK.

Using a command-line interface

> reg add HKLM\System\CurrentControlSet\Services\NTDS\Diagnostics /v "6 Garbage[RETURN] 
Collection" /t REG_DWORD /d 1

Using VBScript

' This code enables logging of DIT whitespace information in the event log.
' ------ SCRIPT CONFIGURATION ------
strDCName = "<DomainControllerName>"  ' e.g. dc1
' ------ END CONFIGURATION ---------

const HKLM = &H80000002
strNTDSReg = "SYSTEM\CurrentControlSet\Services\NTDS\Diagnostics"
set objReg = GetObject("winmgmts:\\" & strDCName & "\root\default:StdRegProv")
objReg.SetDWORDValue HKLM, strNTDSReg, "6 Garbage Collection", 1
WScript.Echo "Garbage Collection logging set to 1"

Discussion

By setting the 6 Garbage Collection diagnostics logging option, event 1646 will get generated after the garbage collection process runs. Here is an example 1646 event:

Event Type: Information Event Source: NTDS Database Event Category: Garbage Collection Event ID: 1646 Date: 5/25/2003 Time: 9:52:46 AM User: NT AUTHORITY\ANONYMOUS LOGON ...