Storm season is back, bringing with it the potential for significant weather events. If you have clients in areas prone to infrastructure disruption, visit the Disaster Recovery Resources guide for preparedness information. Datto recommends performing proactive disaster recovery testing to mitigate potential downtime. See our articles about the importance of disaster recovery testing and Preparing For A Cloud Virtualization Test: Policies, Procedures, And Partner Responsibilities to learn more. For live updates, follow @datto on Twitter.

Restoring A Thick-Provisioned Image Export To VMware ESXi



This article describes the steps to restore a thick-provisioned lazy zeroed VMDK or VMDK-linked image export to a VMware ESXi environment.

Use the VMDK export method if you need to copy the image export as thin-provisioned.


  • Datto ALTO
  • Datto SIRIS


Which file format should I choose?

  • Choose VMDK if neither image build time or storage space considerations on your Datto appliance are a concern.
  • Choose VMDK-linked if image build time or storage space considerations on your Datto appliance are a concern.
    • NOTE: Do not select VMDK-linked if you will need to expand the disk size of the system's VMDK files in the future. The VMDK created during the VMDK-linked export process is a fixed file which references .datto files generated by your Datto appliance, and cannot be resized as a means of increasing available storage space.


To export a thick-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 Image Export (click to enlarge)

  1. Choose the Destination. In Figure 2, the device is sending the restore to a Network Share.
  2. Select VMDK or VMDK-linked as the Format.
  3. Select the desired boot type: MBR, EFI, or Auto Detect.

Figure 2: Export Image (click to enlarge)

  1. Click Export. The Datto appliance will create a clone of the point you selected and share it on the local network.
  2. The GUI will refresh with new options. Copy the NFS VMDK share path to your clipboard.

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

  1. Add the NFS share from the Datto appliance to VMware as a datastore and create the VM if necessary.
  2. Choose a copy method to continue:

Copying the Export to the Datastore via the VMware GUI

Copy the VMDK file(s) and .datto files to the datastore. To do this:

  1. Right-click the datastore you created in Adding a NFS Share from the Datto Appliance to VMware ESXi as a Datastore, and click Browse. You will use this as the Source Datastore in the next steps.

Figure 4: Browse (click to enlarge)

  1. You will see a list of virtual disks displayed, similar to the example shown in Figure 5. Select the disk you'd like to copy, and click the Copy button.

Figure 5: Browsing a Source Datastore (click to enlarge)

  1. In the Select Datastore window, choose the Destination Datastore you'd like to copy the virtual disk to.

    NOTE: If you have an existing VM, or you created a new one, select the folder in the datastore associated with the VM you created. If you do not have an associated VM yet, create a new folder in the destination datastore where the VMDKs are needed.

Figure 6: Selecting a destination (click to enlarge) 

  1. Select the destination datastore and folder, and click Copy. The VMDK will be copied to the destination. Proceed to the Cleanup section of this article to continue.

Technical Notes

  • When you attach the NFS share to VMware as a datastore, you will not see its .DATTO files if you selected VMDK-linked. Instead, you'll see VMDKs listed as FULL Files. However, both the VMDKs and the .DATTO files should copy over.
    • If you notice that the total filesize of the VMDKs is too small after copying, delete the copied virtual disks, return to the Source Datastore, and select Move. The VMDK pointer files will move to the Destination Datastore and leave behind their corresponding .DATTO files. Move these files to the same destination datastore you moved the VMDKs to.

  • The disk image provided by the VMDK export is thick-provisioned. Using the copy method described in this article will result in a thick-provisioned VMDK in the destination datastore. If you wish to copy the VMDK as thin-provisioned, you will need to do so via VMware Converter or through the use of vmkfstools via the ESXi Command-Line Interface (CLI).

  • Do NOT copy the .VMX file if it is present. The .VMX file is only useful when using VMWare Converter and should not be used to manually restore the system. Follow the steps in Creating a New Virtual Machine in VMware ESXi to create a new virtual machine and attach the recovered .VMDK files to the new virtual machine.

Copying the Export to the Datastore via the WMware Command-Line

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

vmkfstools -i /vmfs/volumes/[SourceDataStoreName]/[DriveLetter].vmdk /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 where the disk images will be copied to.


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

Proceed to the Cleanup section of this article to continue.


  1. When the transfer completes, access your ESXi environment. If you have not already, 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, you will need to create one before attaching the virtual disks. The Image Export process does not generate a VMX template. Ensure you add the hard disks when you create the VM template to prevent a transient issue in which VMDK or VMDK-linked files are read as 0 GB in size.
  • Make sure to attach the vmdk file first, followed by c.vmdk, and then any other applicable drives.
  1. 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.
  2. Unmount the NFS datastore you created in Step 10 from your ESXi environment.
  3. 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.

mceclip3.pngFigure 7: Unmount (click to enlarge)

Additional Resources

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