IBM Global Mirror

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Global Mirror is an IBM technology that provides data replication over extended distances between two sites for business continuity and disaster recovery. It provides an RPO (Recovery Point Objective) of as low as 3-5 seconds with adequate bandwidth between the two sites at extended distances with no performance impact on the application at the primary site. It replicates the data asynchronously and then forms a Consistency Group at a regular interval allowing a clean recovery of the application.

The two sites can be on separate continents or simply on different utlility grids. IBM also provides a synchronous data replication method call Metro Mirror, which is designed to support replication at "Metropolitan" distances of (normally) less than 300-km.

Global Mirror is based on existing IBM Copy Services functions: Global Copy and FlashCopy. Global Mirror operations periodically invoke a point-in-time copy at the recovery site, at regular intervals, without impacting the I/O to the source volumes. This provides for a continuously updating, nearly up-to-date copy. Then, by grouping many volumes into a Global Mirror session multiple volumes may be copied to the recovery site simultaneously while maintaining point-in-time consistency across those volumes.

Global Mirror can be combined with a wide area clustering product like Geographically Dispersed Parallel Sysplex (GDPS), HACMP/XD, or CAW to provide for automated failover between sites. This combined solution provides the lowest RTO (Recovery Time Objective) possible and allows most applications to resume productive operation in between 30-seconds and 600-seconds.

The Global Mirror function is available on IBM's enterprise storage devices including the DS8100, the DS8300, the DS6800, the Enterprise Storage Server Models 800 and 750, and the IBM SAN Volume Controller.