How to create a ASM instance in RAC

How to create a ASM instance in RAC:
 Step1.    Start cluster synchronization service:
        >crs_start ora.cssd
                     >crs_stat –t (to check the status)
Step2.   Register ASM instance to OCR
>export ORACLE_SID=+ASM
>srvctl add asm -p $ORACLE_HOME/dbs/init+ASM.ora
              > Start the ASM instance any way you like:
              > srvctl start asm
        or
        > sqlplus "/ as sysasm"
        startup
        and check the status
        > srvctl status asm

Init+ASM.ora contents:
instance_type=asm
remote_login_passwordfile=exclusive
Step3.    Create Disk groups
Two Raw devices d100 and d103 of size 165GB and 20GB respectively allocated to ASM.

> sqlplus "/ as sysasm"
CREATE DISKGROUP DATA_AB01 EXTERNAL REDUNDANCY DISK '/dev/ad/rdsk/d101';

CREATE DISKGROUP FRA_AB01 EXTERNAL REDUNDANCY DISK '/dev/ad/rdsk/d102';