code: def spare_disk(self, disk_xml=None):
          
  
          spare_disk = {}
          disk_types = set()
  
          for filer_disk in disk_xml:
              disk_types.add(filer_disk.find('effective-disk-type').text)
              if not filer_disk.find('raid-state').text == 'spare':
                  continue
  
              disk_type = filer_disk.find('effective-disk-type').text
              if disk_type in spare_disk:
                  spare_disk[disk_type] += 1
              else:
                  spare_disk[disk_type] = 1
  
          for disk_type in disk_types:
              if disk_type in spare_disk:
                  self.push('spare_' + disk_type, 'disk', spare_disk[disk_type])
              else:
                  self.push('spare_' + disk_type, 'disk', 0)
docs: Number of spare disk per type.
  
              For example: storage.ontap.filer201.disk.SATA