A key decision that you must make in planning for a disaster is deciding which licensed functions to use to best suit your environment.
| Licensed function | Description | Advantages | Considerations |
|---|---|---|---|
| Metro/Global Mirror | Three-site, long distance disaster recovery replication | A backup site is maintained regardless of which one of the sites is lost. | Recovery point objective (RPO) might grow if bandwidth capability is exceeded. |
| Metro Mirror | Synchronous data copy at a distance | No data loss, rapid recovery time for distances up to 300 km. | Slight performance impact. |
| Global Copy | Continuous copy without data consistency | Nearly unlimited distance, suitable for data migration, only limited by network and channel extenders capabilities. | Copy is normally fuzzy but can be made consistent through synchronization. |
| Global Mirror | Asynchronous copy | Nearly unlimited distance, scalable, and low RPO. The RPO is the time needed to recover from a disaster; that is, the total system downtime. | RPO might grow when link bandwidth capability is exceeded. |