I have found this article:

https://portal.nutanix.com/page/documents/kbs/details?targetId=kA00e000000XmslCAC

"Convert a disk from Nutanix Volumes to a direct attached disk"

The solution of using volume group is just the opposite, convert a direct attached disk to a volume disk, and attach the vg to the second vm.

I am new with nutanix, I would appreciate any help to share the disk with a second vm.

Regards, 

Ivan 

In the end I have done it without service interruption. 
1- Create the vg with a disk of the same size and attach it to the vm
2- In the VM, add the disk to the same LVM vg as the directly connected disk and move the data to the new disk in the volume group with pvmove.
3- Once the data has been moved, I can delete the old disk, first from the LVM of the vm, and then from the AHV.

Now I am having problems to mount the volume in the new VM. The goal is to share the log volume of several VMs on this new VM. The first thing I have seen, is that I will need to change the vg name at the LVM level of each VM, because in all the VMs is called the same, so there will be conflict in the new VM. And what is happening to me is that the files in the new VM, are frozen in the same state since the filesystem was mounted, the changes that are made on the source machine on these logs are not updated. The mount point is different, I do not know if this can affect, also at first I mounted it in read-only mode, ...

Any help would be appreciated.

My account has already been added to the support contract, I will open a case because the volume sharing does not work.