You can create, suspend, resynchronize, or delete GAD pairs and you can manage pairs in a GAD 3DC delta resync environment.
You should be aware of the following pair operation restrictions:
- Pair operations cannot be performed on volumes that do not have an LU path. Before performing pair operations, make sure that the volumes to be assigned to pairs have at least one LU path defined.
- When connecting the storage system to the host via NVMe-oF, set a namespace for the volume to be operated or to verify the pair status so that the volume can be recognized from the host. The pair operations and the pair status confirmation cannot be performed on the volumes for which the namespace on the NVM subsystem with the NVM subsystem port added is not defined.
- Pair operations cannot be performed during firmware exchange processing. Before performing pair operations, make sure that firmware exchange processing is complete. However, you can perform pair operations from CCI even during firmware exchange processing.
- Pair operations cannot be performed when firmware exchange processing has been interrupted (for example, due to user cancellation or error). Make sure that firmware exchange processing has completed normally before performing pair operations. However, you can perform pair operations from CCI even when firmware exchange processing has not completed.
- If the following status continues while the GAD pair mirroring,
the GAD pair
might be suspended to prioritize the update I/O than mirroring of the GAD pair.
- The availability ratio of the processor in the MP unit to which the primary volume belongs is equal to or more than 70% on the storage system at the primary site.
- There is a large amount of inward traffic of update I/O to the primary volumes on the storage system at the primary site.
- The Write Pending of
the MP unit to which the secondary volume belongs is equal to or more than
65% on the storage system at the secondary site.
When you create or resynchronize the GAD pair, consider the above load status of the storage system at each site.
- If a volume connected to a host via NVMe-oF is used, pair creation can only be performed by using CCI.
- When you create or resynchronize a GAD pair, pair operations might fail if the controller board in the primary or secondary storage system is blocked. Restore the blocked controller board before you perform pair operations.