What is the smallest LVM2 logical volume unit?

Question

Could you ensure me that minimal LVM2 size Unit is one extent to which all sizes are rounded up ?

Is 4MiB the default size of extent for LVM2 ? Can it be configurable or is it the only size ?

Small experiment of try of creating 2B logical volume:

# lvcreate -L 2 r2Ta -n test2b
  Rounding up size to full physical extent 4.00 MiB                                                                                                                     
  Logical volume "test2b" created
# lvdisplay /dev/mapper/r2Ta-test2b  | grep 'LV Size'                                                                                           
  LV Size                4.00 MiB 

Answer 1

Yes, the minimum size is one physical extent. You can specify the PE size when you create the volume group with the -s switch to vgcreate.