SIRIS, ALTO, and NAS: Restoring A Thin-Provisioned Image Export To VMware ESXi with Vmkfstools



This article describes the steps to restore a thin-provisioned VMDK image export to a VMware vSphere environment using vmkfstools (VMware command line).

Use the VMDK / VMDK-linked export method if you need to copy the image export as thick-provisioned.

If you have a licensed version of VMotion, see How to storage vMotion a Datto-managed ESX virtualization to see if you can restore directly via your hypervisor.

To learn more about virtual disk provisioning policies, see VMware's article on the subject (external link).


  • Datto ALTO
  • Datto SIRIS
  • vmkfstools


Export a thin-provisioned disk image for use on VMware ESXi host

1. Access the Datto appliance GUI.

2. Click the Restore tab.

3. Select the system to restore, and then click Export Image.

4. Choose the recovery point that you want to use, and then click Start Restore.

Figure 1: Start Restore (click to enlarge)

5. Choose the Destination. In Figure 2, the device is sending the restore to a Network Share.

6. Select VMDK as the Format.

7. Select the desired boot type: MBR, EFI, or Auto Detect.

Figure 2: Export Image (click to enlarge)

8. Click Export. The Datto appliance will create a clone of the point you selected and share it on the local network.

9. The GUI will refresh with new options. Copy either the Samba or NFS VMDK share path to your clipboard.

Figure 3: CIFS/Samba VMDK share path (click to enlarge)

10. Add the NFS share from the Datto appliance to VMware as a datastore and create the VM if necessary.

Copy and move the datastore using vmkfstools

vmkfstools (external link) is an ESXi command-line tool that you can use to manage virtual disks. 

To copy the datastore from the Datto appliance to a permanent datastore on VMware with thin disk provisioning, use the following command:

vmkfstools -i /vmfs/volumes/[SourceDataStoreName]/[Volume].vmdk -d thin /vmfs/volumes/[DestinationDataStoreName]/[DriveLetter].vmdk
  • The SourceDataStoreName is the datastore you created, which references the NFS share on the Datto appliance.
  • The DestinationDataStoreName is the datastore on your environment to which the disk images will be copied.

Example (Windows):

vmkfstools -i /vmfs/volumes/Datastore/C.vmdk -d thin /vmfs/volumes/HostStorage001/C.vmdk

Once the copy completes, proceed to the Cleanup section of this article to continue.


1. When the transfer completes, access your vSphere environment. Create a new virtual machine or attach the transferred disks to an existing virtual machine as necessary.

2. Make sure that the machine's settings match the needs of your environment. Make any adjustments needed.

  • If your import process requires a VMX template, and the selected snapshot originated from a protected agentless system, you can find a copy of the virtual machine's configuration, as it existed at the time of the backup, in the Image Export files. The file is named configuration.vmx. Before using this file, Datto recommends reviewing and updating its contents to ensure that the naming convention it uses, match your current production environment.
  • Attach the virtual machine's disks, starting with the boot volume (in Windows this would be C.vmdk). and then any other applicable drives. 

3. Boot the virtual machine. Make sure that it boots to the Windows login screen. If the virtualization fails after the first attempt, try again with a different storage controller. If the issue persists, contact Datto Technical Support.

4. After confirming that the virtual machine functions as expected, return to the Export Image screen in your Datto appliance's GUI, and click Unmount to remove the shared clone

Figure 4: Unmount image (click to enlarge)

Additional Resources

Was this article helpful?

3 out of 7 found this helpful

You must sign in before voting on this article.

Want to talk about it? Have a feature request?

Head on over to our Datto Community Forum or the Datto Community Online.

For more Business Management resources, see the Datto RMM Online Help and the Autotask PSA Online Help .

Still have questions? Get live help.

Datto Homepage