The HyperMetro technology provided by storage devices is used for same-city DR. Remote replication functions provided by storage devices are used to replicate application data from a production data center to a DR center for remote DR.
For details about storage HyperMetro (SAN) and Asynchronous Replication (SAN) of the DR Star networking, see About DR Star in the storage device online help.
- Storage devices are deployed for a production data center and a same-city DR center to implement HyperMetro DR. For details about the HyperMetro DC Solution, see DR Principles(HyperMetro (SAN)).
- Asynchronous remote replication is used between a same-city DR center and a remote DR center. The principles for asynchronous remote replication are as follows:
- After an asynchronous remote replication relationship is set up between a primary LUN at a production site and a secondary LUN at a DR site, an initial synchronization is implemented.
- If the primary LUN receives a write request from a production host during the initial synchronization, data is written only to the primary LUN.
- After the initial synchronization is complete, Slave LUN Data Status is Synchronized or Consistent. (If the host sends no write request during the initial synchronization, Slave LUN Data Status is Synchronized; otherwise, Slave LUN Data Status is Consistent.). Then, I/O requests are processed according to the procedure in Figure 1.
- The primary LUN receives a write request from a production host.
- After data is written to the primary LUN, a write completion response is immediately returned to the host.
- Incremental data is automatically synchronized from the primary LUN to the secondary LUN based on the user-defined synchronization period. (If the synchronization type is Manual, users need to trigger the synchronization manually.) Before the synchronization, the storage system creates snapshots for the primary LUN and secondary LUN.
- The snapshot generated for the primary LUN ensures data consistency between the primary LUN and the secondary LUN during data synchronization.
- The snapshot for the secondary LUN provides backup for the data on the secondary LUN before synchronization. This ensures that data on the secondary LUN is usable even when an exception occurs during synchronization.
- During the synchronization, data is read from the snapshot of the primary LUN and copied to the secondary LUN.
- After the synchronization is complete, the snapshots of the primary and secondary LUNs are canceled, and the next synchronization period starts.
