Technical stuff that might be useful

Category: Windows

  • Windows update CAB file build up

    We’ve had a spate of PCs filling up their disks recently, and it seems to stem from a bug in Windows update.

    The issue occurs because an accumulated update log file grows, and generates a series of CAB files “cab_xxx_x” in the temp folder (normally c:\windows\temp).

    The issue isn’t new, I found references to it dating back to 2012. It seems to be a bug with Windows Update on Windows 7 and Windows Server 2008 R2.

    If you just delete the CAB files they will come back. The solution seems to be to do the run the following commands:

    net stop wuauserv 
    net stop trustedinstaller

    rmdir /s c:\windows\softwaredistribution
    del c:\windows\temp\*.* /s /f /q

    net start wuauserv
    net start trustedinstaller

    If you don’t stop the services first you may not be able to delete the files.

    Next step is to run Windows update. Windows 7 and 2008 R2 have a huge number of updates to do from a fresh install, which is why this log file builds up. Deleting the files resets the log, but if there are still too many to do the issue may come back.

    I set up a monitor on SolarWinds N-Central to check all our clients temp folder sizes and to run the above as a script if it was over 15GB. That should prevent any space issues on-going.

    Alternatively just upgrade to Windows 10 and Server 2016 – they don’t have this problem.

  • Manually syncing Azure AD

    When Azure Connect is setup the quickest way to fire off a manual sync is through powershell.

    For a full sync (new accounts etc):

    import-module adsync
    Start-ADSyncSyncCycle -PolicyType Initial

    For a incremental sync (faster but not as thorough):

    import-module adsync
    Start-ADSyncSyncCycle -PolicyType delta

    I normally save these as .ps1 files on the desktop of the server to I can quickly run them.

    [3cx-clicktotalk id=”89″ title=”Live Chat & Talk item 1″]

  • Moving FSMO Roles with Powershell

    Another article about a command that I can never remember the syntax when I need it.

    The information here is from: https://social.technet.microsoft.com/wiki/contents/articles/6736.move-transfering-or-seizing-fsmo-roles-with-ad-powershell-command-to-another-domain-controller.aspx

    To transfer all roles use:

    Move-ADDirectoryServerOperationMasterRole -Identity “Target-DC” -OperationMasterRole SchemaMaster,RIDMaster,InfrastructureMaster,DomainNamingMaster,PDCEmulator

    To seize the roles append -Force.

    You can also substitute the role names with numbers, making a more manageable:

    Move-ADDirectoryServerOperationMasterRole -Identity “Target-DC” -OperationMasterRole 0,1,2,3,4 -Force

    Much easier to remember than trying to remember which bit of the gui does which role.

    Older servers use ntdsutil.exe:

    https://support.microsoft.com/en-gb/help/255504/using-ntdsutil.exe-to-transfer-or-seize-fsmo-roles-to-a-domain-controller

  • Using subst to map a drive to help restore from a volume shadow copy

    I needed to copy only missing files from a volume shadow copy back to a clients share after clearing out crypto malware encrypted files, and I found a new favourite command:
    subst drive1: drive2:path
    Substitutes a path for a drive letter, for example:
    subst x: c:\users\adam\desktop

    maps x: to my desktop in my profile.

    Where this came in particular handy for me we using robocopy to restore files an folders out of a volume shadow copy (previous version).

    I wanted to run robocopy a: b: /xc /xn /xo /s which only copies missing files, and does not copy existing files – regardless of age or difference, to extract missing files from the shadow copy.

    So first I found the path to the file by right clicking on a file in the shadow copy and copying the location then running subst:

    subst x: "\\localhost\C$\@GMT-2016.10.24-14.01.30\Server Shares\Company"

    I could then run my robocopy from the x: drive.

    Finished off with subst x: /d to remove the drive mapping.

    Useful write up here:

    https://chaoliu12.wordpress.com/2013/02/11/restore-files-from-shadow-copy/

    And subst technet article here:

    https://technet.microsoft.com/en-gb/library/bb491006.aspx

  • User Shell Folders location in the registry

    I’m always having to look this up, for some reason the registry location just doesn’t stick in my head.

    User Shell Folders (i.e. My Documents, Desktop, Favorites):

    HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders

    Useful if you want to know if Folder Redirection is working.