Instead of adding an extent to a VMFS datastore, you can increase the size of an existing datastore. Use the
vmkfstools -G command.
You might increase the datastore size after the underlying storage had its capacity increased.
The command uses the following option:
-G|--growfs device device
vmkfstools --growfs /vmfs/devices/disks/disk_ID:1 /vmfs/devices/disks/disk_ID:1