For clone disk and clone vm without vcenter :
cd /vmfs/volumes/Datastore01Raid10
/vmfs/volumes/537dfea4-903a2d25-a8c3-00237da1046c # ls
SRVAPP01 SRVDC02 win2008R2ent
/vmfs/volumes/537dfea4-903a2d25-a8c3-00237da1046c # mkdir template2008
vmfs/volumes/537dfea4-903a2d25-a8c3-00237da1046c # vmkfstools -i SRVDC02/SRVDC02.vmdk template2008/template2008.vmdk
Destination disk format: VMFS zeroedthick
Cloning disk ‘SRVDC02/SRVDC02.vmdk’…
Clone: 100% done.
/vmfs/volumes/537dfea4-903a2d25-a8c3-00237da1046c #
And select custom configuration for add existing disk
and after select other option for the disk “Use an existing virtual disk”
and select the vmdk create .