The relationship status changes to c onsistent 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.  Table 11-10 lists the combinations of FlashCopy and MM/GM functions that are valid for a  single volume. Table 11-11 lists the MM/GM configuration limits. 11.6.21 Valid combinations of FlashCopy, Metro Mirror, and Global Mirror  11.6.22 Remote Copy configuration limits Table 11-10 Valid combination for a single volume Table 11-11 Metro Mirror configuration limits FlashCopy Metro Mirror or Global Mirror  source Metro Mirror or Global Mirror  target FlashCopy Source Supported Supported FlashCopy Target Supported Not supported Parameter Value Number of Metro Mirror or Global Mirror  Consistency Groups per system 256  Number of Metro Mirror or Global Mirror  relationships per system 8192 Number of Metro Mirror or Global Mirror  relationships per Consistency Group 8192 Chapter 11. Advanced Copy Services  533