For a Multi-Target Metro/Global Mirror configuration (where the primary has a
Metro Mirror relationship with one PPRC pair and a Global Mirror relationship with the
other) refer to IBM DS8870
Version 7 Release 4 Multiple Target Peer-to-Peer Remote Copy rather than using this
topic.
In a Metro/Global Mirror configuration, if you lose access to the storage unit at the local site, the Global Copy relationship is intact and Global Mirror is still operational. Through the use of FlashCopy® operations and consistency groups, consistent data is achieved at the remote site. However, you are left without the local site until all recovery operations have been performed to recover the local site.
A three-site Metro/Global
Mirror configuration provides the following
recovery options at the alternate sites if a failure occur:
- If an outage occurs at the local site, recovery operations can begin at the intermediate site. Global Mirror continues to mirror updates between the intermediate and remote sites, maintaining the recovery capability at the remote site.
- If an outage occurs at the local site, recovery operations can begin at the remote site and preparations can be made to resynchronize the local site when it recovers from its disaster. Once in recovery mode at the remote site, another Global Mirror session can be setup and put into operation using the former intermediate as its new remote site. This new Global Mirror session will provide additional disaster recovery solution while operating at the remote site.
- If an outage occurs at the intermediate site, data at the local storage unit is not affected. Applications continue to run normally.
- If an outage occurs at the remote site, data at the local and intermediate sites is not affected. Applications continue to run normally. The intermediate storage unit maintains a consistent up-to-date copy.
- If both the local and intermediate sites are lost, the scenario is similar to a two-site scenario when access to the local storage unit is lost. Recovery must be achieved using the last consistent point-in-time copy at the remote site.