text: The relationship status changes to consistent synchronized when the resynchronization 
  process completes. The relationship automatically resumes replication after the temporary 
  loss of connectivity. 
  
  Change Volumes used for Consistency Protection are not visible and manageable from the 
  GUI because they are used for Consistency Protection internal behavior only. 
  
  It is not required to configure a secondary change volume on a MM/GM (without cycling) 
  relationship. However, if the link goes down or the secondary volume is offline, the 
  relationship goes in to the Consistent stopped status. If write operations take place on either 
  the primary or secondary volume, the data is no longer synchronized (Out of sync). 
  
  Consistency protection must be enabled on all relationships in a Consistency Group. Every 
  relationship in a Consistency Group must be configured with a secondary change volume. If a 
  secondary change volume is not configured on one relationship, the entire Consistency 
  Group stops with a 1720 error if host I/O is processed when the link is down or any secondary 
  volume in the Consistency Group is offline. All relationships in the Consistency Group are 
  unable to retain a consistent copy during resynchronization. 
  
  The option to add consistency protection is selected by default when MM/GM relationships 
  are created. The option must be cleared to create MM/GM relationships without consistency 
  protection. 