Note the following behaviors for split pairs:
- The primary system stops performing update operations to the S-VOL. It may or may not continue accepting write I/Os to the P-VOL depending on the P-VOL fence level setting.
- If an update fails, the primary system reports a unit check and notifies the host that Write fails. This ensures that both the host system and application program regard the write operation to the P-VOL as failed.
- If the primary system accepts subsequent write I/Os for a split P-VOL, the system records the updated data in the P-VOL tracks as differential data. When a split pair is resynchronized, the primary system copies the out of sync P-VOL tracks to the S-VOL as differential data.