Exadata ASM : Relation between hidden parameter _asm_ausize and diskgroup au_size

Hi to all,

We have an EXADATA machine, installed with ASM 12C.

The default allocation Unit Size on this machine is '4194304'.

On any instances, ASM and others, the hidden parameter '_asm_ausize' is set by default to '1048576'.

I ask you that question  because  I have read, in the document ID 368055.1,  the parameter '_asm_ausize'  is changed to set this hidden parameter to the same value as the 'Allocation Unit Size'

SQL> select x$ksppi.ksppinm name, x$ksppsv.ksppstvl value, x$ksppsv.ksppstdf isdefault, KSPPDESC

     from x$ksppi, x$ksppsv

     where x$ksppi.indx = x$ksppsv.indx