• Adding Disks to a Disk Group
• Dropping Disks from Disk Group
• Replacing Disks in Disk Group
• Renaming Disks in Disk Group
• Resizing Disks in Disk Group
• Changing Diskgroup Attributes
• Undropping Disks in Disk Group
• Creating ADVM Volumes

https://onlinedbalearning.blogspot.com/2018/07/altering-asm-disk-groups.html