Вы не можете указать количество экстентов, создающих PV ... PV - это просто устройство, которое «выглядит» как жесткий диск. Вы можете сделать это, создав LV:
-l, --extents LogicalExtentsNumber[%{VG|PVS|FREE|ORIGIN}]
Gives the number of logical extents to allocate for the new logical volume. The number can
also be expressed as a percentage of the total space in the Volume Group with the suffix %VG,
as a percentage of the remaining free space in the Volume Group with the suffix %FREE, as a
percentage of the remaining free space for the specified PhysicalVolume(s) with the suffix
%PVS, or (for a snapshot) as a percentage of the total space in the Origin Logical Volume
with the suffix %ORIGIN.
С уважением.