To use a NAS for virtual machines therein or simply recover backups turn requires that the virtual machines are accessible via a UNIX (NFS) or Windows share sharing.
To share a folder on a NAS, you rely on the tutorial performed under FreeNAS named "FreeNAS - Create a shared UNIX (NFS)".

1. Mount a network location (NFS)
2. Transfer machine on the ESXi server
3. Add the virtual machine in the inventory

1. Mount a network location (NFS)

Once the split is made, start "vSphere Client" and click the "Inventory" icon and go to the "Settings" tab. In the left menu, click on "Storage" and then click "Add Storage".

Select "Network File System" and click "Next".

Enter the IP address of your NAS and specify the network path (mount point) sharing with you performed on your NAS. Then enter a database name at the bottom.

Then, click "Finish".

Your NFS share is displayed.

2. Transfer machine on the ESXi server

Right click on your NFS share and click "Browse the database".

If you want to recover is stored on your NAS to transfer it to your ESXi server machine, select the folder of the machine to move to another new database and click the "icon" that appears on the image.

ESXi warns you that if it is a folder containing the files of a virtual machine, it should be added to the inventory after the transfer. Click "Yes".

Select the database and the folder to copy the contents of the file to upload and click "Move".

The transfer of the machine takes time depending on the speed of the network and the performance of ESXi server and the remote NAS.

3. Add the virtual machine in the inventory

Once the transfer is complete, right-click the database to which you moved the folder and click "Browse the database".

Go to the folder of the machine transferred and right click on the file (type : Virtual Machine) ".vmx". And click "Add to Inventory".

The machine name is set automatically but you can modify it.

Select the server to be used for this virtual machine running.

Finally click "Finish".

You will see your virtual machine displayed in the "Virtual Machines" tab.

To avoid network problems and conflicts, you must specify whether you moved or copied. If you don't know what answer select, it is recommended to select "I copied it".