When you are deploying new VMs with System Center Virtual Machine Manager 2008 R2 you have the option to mount an ISO image to install the OS from. When you do this the default behaviour is to copy the ISO file from the library to the location where the VM is being created. This causes two things to happen, first you have to copy the ISO over the network and second you end up losing that storage space as the ISO remains in the VM file location.
SCVMM allows you the option to share the ISO rather than copying it. While the data in the ISO still gets copied over the network during the install, the ISO isn’t saved to the VM file location and in the long run this will save you some space.
To implement this you need to configure some security settings to allow this to work. If you don’t you will get the following error message.
The first thing you need to do is add the SCVMM service account to both the Share and NTFS Security permissions to the SCVMM library share. You also need to add each of your Hyper-V host servers to both the Share and NTFS Security permission. They will need Read permissions at minimum.
Next you have to configure constrained delegation for the Hyper-V hosts. To do this open up AD Users and Computers, locate the Hyper-V server(s) and open up the properties for each. Select the Delegation tab. Next click the “Trust this computer for delegation to specified services only” and “Use any authentication protocol” radio buttons. Finally click Add.
Select the cifs Service Type and click OK
Click OK to close out the properties page and you are done.
