ALTER DISKGROUP
    { diskgroup_name
        { add_disk_clause | drop_disk_clause }
            [, { add_disk_clause | drop_disk_clause } ]...
        | resize_disk_clauses
        } [ rebalance_diskgroup_clause ]
        | {rebalance_diskgroup_clause                                    
          | check_diskgroup_clause
          | diskgroup_template_clauses
          | diskgroup_directory_clauses
          | diskgroup_alias_clauses
          | drop_diskgroup_file_clause
          } 
    | { diskgroup_name
          [, diskgroup_name ]...
      | ALL 
      }
      { undrop_disk_clause
      | diskgroup_availability
      }
    }