Monday, October 8, 2012

Windows 2008 R2 Cluster Tuning for FileServers (Part One)


I have always believed that Windows 2008 R2 Clustering is two steps forwards and one step back for Microsoft. I look after such a cluster that happens to have 12,000 shares. This requires some special considerations. In part one I will describe what happens when you try to move/delete or rename a folder.

When you rename, delete or move a folder on Windows 2008, the operating system has to check to see whether the action will break a share. In order to do that it will look to the registry for the folder name. Share names are held in:

HKLM\\Resources\\Parameters.

If there is a share corresponding to the folder then it will pop the classic message telling you that the action you are about to perform will stop the share. If you have 12,000 of them then this will take a very long time and during that time, explorer will appear to hang. I think it does come back eventually, although the operating system might decide to restart itself before it completes. Certainly if you click on anything it will report that explorer has crashed. Here is the real beef - if the cluster service decides to perform a health check while explorer is in the weeds, the cluster will failover.

Currently there is only one solution, and that is to disable that behavior so that explorer no longer checks to see if you are going to break a share. This is achieved by deleting the following key:

HKEY_CLASSES_ROOT\Directory\shellex\CopyHookHandlers\Sharing
 
Of course you will need to reboot.
 
Cheers! See you in part two...

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