Hyper-V Server 2012 won’t mount ISO from a network share

Few days ago I installed Hyper-V Server 2012, Microsoft’s free virtualization platform and the equivalent of VMware ESXi.
The very first thing that I was stuck with is that Hyper-V Manager available through RSAT doesn’t have an option to mount an ISO or capture a drive from a machine on which is running. Instead it gives you drives of the Hyper-V host, and that would of course require you to have an ISO or the disc itself present on the host.

For most of us this is very inconvenient, we like the ability to mount an ISO from a network share or our machine. One would think, this a Windows box, no problem, i will map a network drive with my ISOs. The mapping would succeed, but mapped drive (letter) will not be visible in Hyper-V manager when trying to mount an ISO. Ok, the next step that the one would consider is mounting from UNC share directly, but that would also fail, with the message “‘VM’ failed to add device ‘Virtual CD/DVD Disk'” & “User account does not have permission required to open attachment”.

The cause of this is that the Hyper-V is intended to run with VMM Library Server and to mount files from it, not any random share. To circumvent this:

You need to assign full NTFS and share permissions to computer account of Hyper-V on a shared folder with ISO’s you want to mount.
In AD on the computer account of Hyper-v machine delegate specific service ‘cifs’ to the machine you want your ISO’s mounted from, microsoft calls this constrained delegation.

Here is step by step procedure for the constrained delegation:

Go to Active Directory Users and Computers
Find the Hyper-V server computer account and open up its properties.
Go to Delegation tab.
Select Trust this computer for delegation to the specified services only radio button.
Click the Add button.
Click the Users or Computers… button.
In the Add Services window, click Users or Computers and enter the computer account that will act as a library server and click OK.
Select the cifs Service Type and click OK.

The resulting setup should look something like this:

You could reboot the Hyper-V server just for the good measure.

20 comments on “Hyper-V Server 2012 won’t mount ISO from a network share”

Thanks! This helped me out a ton!

This does not work…

“You need to assign full NTFS and share permissions to computer account of Hyper-V on a shared folder with ISO’s you want to mount.”

What is the computer account of Hyper-V? Is this an A.D. user?

Zarko on February 20, 2015 at 17:36 said:

Computer accounts are AD objects like users. They do not appear in search by default but you can assign permissions to them the same way you would for users.

Reply

Thomas – Is there a similar solution if I do not have an AD and if this a home lab with a NAS device?

Thanks, this really helped!

I have a lab in my home and I don’t want to setup AD, apart copy to local drive, any other workaround solution? Thanks!

Awesome. Worked after rebooting the Hyper-V server.

Absolutely required the Hyper-V server to be rebooted.

Thank you!!

Could not figure this one until I found your post, thank you thank you! To others, I did not need a restart of my HV (thank goodness) to have the permissions take effect… perhaps the token system in Active Directory is different for computers than it is users, so the need to log out/log in isn’t needed for new permissions to take effect?

Also, to those trying to install an ISO (if you say burn an ISO as a file (not an extracted image) to a disc), if it is not working copy and paste the ISO to the hyper-v drive (or your windows share if you got the above working), as Hyper-V has trouble reading image formats that are sparsed.

I did have to reboot the Hyper-V server but this worked a charm! Thank you so much.

Excellent, thanks for the info

Thanks! It worked for me.

This does not work.

Another convoluted and completely unnecessary mess to get something that should be simple working. Nice job Microsoft.

Worked for me , thanks for sharing. I also had to reboot the Hyper-V host though. Fortunately it’s in a 6-node 2016 Hyper-V cluster, so I could live migrate the VMs elsewhere first.

The next question though, is going to be how to delegate for all the hosts using a GPO or something…

Thanks alot. This really helped me and the problem was solved.

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Thomas on October 12, 2014 at 23:57 said:

Thanks! This helped me out a ton!

Z_H on November 11, 2014 at 17:24 said:

This does not work…

James on January 21, 2015 at 01:24 said:

“You need to assign full NTFS and share permissions to computer account of Hyper-V on a shared folder with ISO’s you want to mount.”

What is the computer account of Hyper-V? Is this an A.D. user?

- Zarko on February 20, 2015 at 17:36 said:
  
  Computer accounts are AD objects like users. They do not appear in search by default but you can assign permissions to them the same way you would for users.
  
Rajesh. R on January 26, 2015 at 16:06 said:

Thomas – Is there a similar solution if I do not have an AD and if this a home lab with a NAS device?

Martin on March 24, 2015 at 12:08 said:

Thanks, this really helped!

Fred on April 1, 2015 at 17:51 said:

I have a lab in my home and I don’t want to setup AD, apart copy to local drive, any other workaround solution? Thanks!

Paul vc on February 2, 2016 at 23:06 said:

Awesome. Worked after rebooting the Hyper-V server.

Jacmac1 on March 27, 2016 at 16:45 said:

Absolutely required the Hyper-V server to be rebooted.

Keith on April 2, 2016 at 22:32 said:

Thank you!!

nate on September 18, 2016 at 21:40 said:

Could not figure this one until I found your post, thank you thank you! To others, I did not need a restart of my HV (thank goodness) to have the permissions take effect… perhaps the token system in Active Directory is different for computers than it is users, so the need to log out/log in isn’t needed for new permissions to take effect?

nate on September 18, 2016 at 21:43 said:

Also, to those trying to install an ISO (if you say burn an ISO as a file (not an extracted image) to a disc), if it is not working copy and paste the ISO to the hyper-v drive (or your windows share if you got the above working), as Hyper-V has trouble reading image formats that are sparsed.

Scott on October 13, 2016 at 15:29 said:

I did have to reboot the Hyper-V server but this worked a charm! Thank you so much.

SuperPlay on November 23, 2016 at 17:36 said:

Excellent, thanks for the info

Someshwar Rao on June 19, 2017 at 12:31 said:

Thanks! It worked for me.

zeldasmask on March 9, 2018 at 02:59 said:

This does not work.

Salty on April 3, 2018 at 15:46 said:

Another convoluted and completely unnecessary mess to get something that should be simple working. Nice job Microsoft.

Steve C on August 7, 2018 at 16:19 said:

Worked for me , thanks for sharing. I also had to reboot the Hyper-V host though. Fortunately it’s in a 6-node 2016 Hyper-V cluster, so I could live migrate the VMs elsewhere first.

The next question though, is going to be how to delegate for all the hosts using a GPO or something…

Babaseyi Omisade on March 12, 2019 at 17:26 said:

Thanks alot. This really helped me and the problem was solved.

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