Thursday, June 3, 2010
Recently, I added a couple of VMs (Windows 2008 Server R2) from the same image. I did sysprep on the original image and just duplicate the VHD thinking that the sysprep process would reset the original SID. Depending on which point that you capture the VHD image after sysprep (i.e. SID is fixed once the Win7 logo appears), all subsequent duplicate VHD may still share the same SID as the first duplicate. I didn't realise it until I failed to add the duplicate VMs to a same security group. Hence, it's always recommended to capture the image right after the sysprep shutdown, so that you can re-use the same image again and again. (Hint: always shut and do not reboot after sysprep, which SID will be fixed during the initial booting process).
In case of suspected SID duplication, there is this wonderful "name2sid" to find out if there's duplicate SID on the domain. Download it and check it against other servers, as well as the domain e.g.
name2sid Host02 and so forth
And there is also this blog post that mentioned about how to build an unattended installation XML and automated sysprep on the latest W2K8 R2 and Win7 images.