Create Oracle ASM disk and alter / create ASM DiskGroup

First Storage team adds LUN to server on which ASM disk addition is going to be perofmed

Once LUN is attached to Server, System Admin scans the LUN and defines some name to it

ls -ltr /dev/mapper/* --
Considering /dev/mapper/DATA01 is the raw disk provided by System Admin

First check the list of ASM disks already available on server
/etc/init.d/oracleasm listdisks >> Lists the ASM disks

/etc/init.d/oracleasm createdisk DATA /dev/mapper/DATA01 - Creates ASM disk

Once ASM disk DATA is created, scan the disk to all the nodes in the cluster
/etc/init.d/oracleasm scandisks >> This needs to be done to all nodes

/etc/init.d/oracleasm listdisks >> List again the ASM disks

You will be able to locate DATA in your ASM disks

Now for adding this DATA into ASM DiskGroup

Login to ASM through grid "/ as sysasm"

Check the asm_diskstring parameter while adding the disk to DG
show parameter asm_diskstring >> This parameter defines the PATH of ASM disk
considering this set as ORCL:

Command to add ASM disk to ASM DiskGroup
sqlplus "/ as sysasm" >> from grid
alter diskgroup DATA_1 add disk "ORCL:DATA";

If you want to create separate diskgroup then below command

create diskgroup DATA_1 EXTERNAL REDUNDANCY disk "ORCL:DATA";