ASM disk groups are the foundation of ASM. It is where your data will be stored. ASM disk groups can be allocated to raw disk, cooked disk. To add a ASM disk group you first need to set the ASM_DISKSTRING parameter. You can then add disk groups to your ASM instance.
This is a companion discussion topic for the original entry at https://blog.toadworld.com/configuring_26_managing_asm_disks#:~:text=To%20remove%20an%20ASM%20disk%20group%20you%20use,once%20the%20prompt%20returns%2C%20the%20diskgroup%20is%20deleted.