Once you installed grid software and all the Disk are formatted from raw disk by System admin. Then you could proceed to create asm instance and map those Disk(s) with ASM instance. There are multiple ways to setup ASM instance however here we are going to see the silent method using asmca. Below is the command needs to run after setting grid home.
Run Below command from bin directory of grid home where asmca binaries are present.Once asmca completes successfully ,ASM instance gets created ,DISK(s) gets mounted and ASM instances gets started.
[oracle@db-test-01 bin]$ export ORACLE_HOME=/u01/grid/oracle/product/11.2.0/grid_1
[oracle@db-test-01 bin]$ cd $ORACLE_HOME/bin
[oracle@db-test-01 bin]$ ./asmca -silent -configureASM \ -sysAsmPassword Password \ -asmsnmpPassword Password \ -diskGroupName DATA \ -diskList ‘/dev/oracleasm/disks/DATA01’ \ -redundancy EXTERNAL \ -au_size 1 \ -diskString ‘/dev/oracleasm/disks/*’
ASM created and started successfully.
Disk Group DATA created successfully.
Oracle Database with Vishal 