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© Rakhesh Sasidharan

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Asynchronous processing of Group Policy Preferences

My XenApp servers are set to process their GPOs synchronously (because I apply folder re-direction via GPO) and unless I do it synchronously there’s a chance that the user could login without folder redirection and only on the next login will folder redirection kick in.

However I have a bunch of registry keys I am setting via Group Policy Preferences (GPPs) and these take a long time. Eventually I decided to remove these from GPP and set in the default profile itself, and I have to figure out what to do later on when I need to make changes etc (I guess that’s still better as I only need to target the keys that need changing). But before I did that I was reading into how I can set GPPs to run asynchronously. I am ok with the registry keys being set after the user is logged in.

Well, turns out you can use Item Level Targeting (ILT) to have the GPP apply only in non-synchronous mode. I found this via this forum post.

If you want to do this en-masse for all your GPP registry keys you can edit the XML file itself where the GPP settings are stored. (Which is a cool thing about GPPs by the way – I hadn’t realized until now. All GPP settings, such as registry keys, shortcuts, etc. are stored in XML files in the policy. You can copy that XML file elsewhere, make changes, delete the GPP settings and copy paste the XML file into the GPP).

Anyhoo – in the XML file if your existing line for a setting is like this one (:

Add a new line like this after the above:

This adds a filter to that setting causing it to run only if the GPO mode is not synchronous.

This didn’t seem to make much of a difference in my case (in a very unscientific observation of staring at the screen while GPOs are being applied :)) so  I didn’t go down this route eventually.

On this topic, FYI to myself. By default GPPs are processed even if there is no change to the GPP. This is not the expected behavior. GPPs are called “preferences” so the impression one might get is that they set preferences, but let users change the settings. So I could have a GPP that sets an environment variable to something. The user could change it to something else. Since I haven’t changed the GPP after this, I wouldn’t expect GPO processing to look at the GPP again and re-set the environment variable. But that’s not what happens. Even if a GPP hasn’t changed, it is reconsidered during the asynchronous and background processing and re-applied. This can be turned off via GPO by the way. Lookie here: Computer Configuration\Administrative Templates\System\Group Policy\.

Totally unrelated, but came across as I was thinking of ways to apply a bunch of registry settings without resorting to GPPs: a nice article on the RunOnce process in Windows. Brief summary (copy pasted from the article):

  • The Windows registry contains these 4 keys:
  • HKLM\Software\Microsoft\Windows\CurrentVersion\Run
  • HKCU\Software\Microsoft\Windows\CurrentVersion\Run
  • HKLM\Software\Microsoft\Windows\CurrentVersion\RunOnce
  • HKCU\Software\Microsoft\Windows\CurrentVersion\RunOnce

HKCU keys will run the task when a specific user, while HKLM keys will run the task at first machine boot, regardless of the user logging in.

The Run registry keys will run the task every time there’s a login. The RunOnce registry keys will run the taks once and then delete that key. If you want to ensure that a RunOnce key is deleted only if its task is run successfully, you can prepend the key name value with an exclamation mark ‘!’.

 

Asynchronous processing of Group Policy Preferences by rakhesh is licensed under a Creative Commons Attribution 4.0 International License.