How to change a virtual machine's hard disk -vmdk- (that already created and be in use) from thin to thick?

1- Power off the virtual machine.2- Right-click the virtual machine in the inventory.3- Click Edit Settings.4- Click the Hardware tab and select the appropriate hard disk in the Hardware list (Check if it is Thin Provision or Thick Provision, if it is Thin continue).5- Click Cancel to exit out of Virtual Machine Properties dialog box.6- Click the Summary tab of the virtual machine.7- Under Resources, right-click the datastore where the virtual machine resides and click Browse Datastore.8- Double-click the virtual machine folder to display the  .vmdk file.9- Right-click the .vmdk file, and click Inflate. The Inflate option converts the disk to thick provisioned.10- Reload the .vmx file.

First and foremost no changes can be made in a VM in open state, in order to make any changes in VM hardware setting you will have to turn off the VM. Please find the steps below:

1) Navigate through the folder and reach the one containing the virtual disk

2) Select the .vmdk file and right-click on it, select Inflate

3) wait a couple of minutes and the operation will be completed

Thats all. :-) Hope this solve your issue.

1. V-Storage .. Migrate the VM from Disk to Disk. then you can change the type of Disk.

2. Convert the VM using vCenter Converter.

Power off VM

Go to Datastore Where VM is sitting

Open Datastore, Navigate to VM

Select VM VMDK, Click Inflate.

That's it.

Always starting by powering off virtual machines, then the first thing to do is to have a complete backup in place. To start the process, in VSphere Client, after powering off the virtual machines, right clicking Edit Settings to get the Virtual Machines properties and moving to hardware to change the hardisk type from the hardware list.

Then in summary under resources, by moving to datastore where the virtual machines is residing, browse to the virtual machine folder and move to the vmdk file and need to right click and hit Inflate option to convert the disk to Thick provision.

By doing storageMigration we get an option where we can select virtual harddisk from thik to thin, thin to thik.

Do storage Vmotion by changing thick to thin (vice versa) or browse disk file and inflate

We can storage migrate the VM and change the type of vmdk from thin to thick.

1. Turn off the VM.

2. Go to Datastore Browser.

3. Navigate to the VM specific folder (or where the .vmdk is present).

4. Right on .vmdk and click 'Inflate'

If the VM is in ON state, then Migrate the VM to other datastore using storage vMotion. Then you will get all the hard disk options 

Do Storage Motion to new datastore and chnage the format/type of disk  to thick.