Cannot Create a VMDK Larger than 16TB in VMware vSphere ESXi 5.5

When creating a new virtual machine with a virtual machine disk (VMDK) or adding a VMDK to an existing virtual machine over 16TB in the vSphere client 5.5, you receive the following error:

«The disk capacity entered was not a properly formed number or was out of range. It has been replaced with the nearest acceptable value.»

Figure 1: Error Notification


The vSphere Client for 5.5 will only allow you to create a maximum of 16TB VMDKs.

Use the web client instead of the vSphere Client.
If you cannot use the web client, then you can do a workaround via command line :

  • Connect to the server via SSH :
  • Navigate to your VM’s directory :
    • # cd /vmfs/volumes/<datastore>/<vm>
      • Example :
        • # cd /vmfs/volumes/datastore1/testvm
  • Create new VMDK :
    • # vmkfstools -c <size> <newvmdk> -a lsilogic -d thin
      • Example (creates a 25T thin provisioned vmdk named «testvm2.vmdk» with a lsilogic adapter) :
        • # vmkfstools -c 25t testvm2.vmdk -a lsilogic -d thin
  • Add VMDK to existing VM :
    • Right click on VM and click on ‘Edit Settings
    • Click on the ‘Add‘ button at the top of the window
    • Click on ‘Hard Disk‘ and then click on the ‘Next‘ button
    • Select the ‘Use an existing virtual disk‘ radial and then click on the ‘Next‘ button
    • Select the newly created VM and then click on the ‘Next‘ button
    • Click on the ‘Next‘ button
    • Click on the ‘Finish‘ button
    • Ignore the informational messages
    • Click on the ‘OK‘ button to exit out of the VM properties