How to Multiplex Controlfiles - ASM

With the database open or mount(ed)

Show parameter control or “select name from v$controlfile”

  note the controlfile name

startup nomount

rman target /

restore controlfile to '+DESTDG' from '+SOURCEDG/DB/controlfile/Current.[filenumber]';

restore controlfile to '+DESTDG' from '+SOURCEDG/DB/controlfile/Current.[filenumber]';

Set environment for asm

asmcmd find . Current*

  Note the additional 2 controlfile names

Set environment for database

alter system set control_files='+DESTDG/DB/controlfile/Current.[filenumber]','+DESTDG/DB/controlfile/current.[filenumber]','+DESTDG/DB/controlfile/current.[filenumber]' scope=spfile;

startup

show parameter control