Zeroize a thin provisioned disk

[Topogigio]

Hi,
I run pfSense on a Cloud provider that offers a vCloud environment where disks are create in thin provisioning (..... Aruba, if you want to avoid it...).

Is there any safe way to "fill up the disk then go back" to force vmware to expand the vmdk to all assigned space?
BTW I have this error: https://forum.netgate.com/topic/167882/scsi-error-on-vm/9

thanks