Tip of the Day: Namespaces and Failover a Quick Overview

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  • 1.  Tip of the Day: Namespaces and Failover a Quick Overview

    Posted 01-06-2015 06:46:00 PM
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    A namespace contains a set of replicated objects. These objects are read-only and disabled while replication are ongoing. To view replicated objects, select the System > Namespaces menu item (or namespace in the CLI). From this dialog you can browse the contents of namespaces, as well as fail over or delete individual namespaces. As described in the Replication">">Replication Overview topic, only databases (dSouces and VDBs) and environments are included within the namespace.

    *Deleting or failing over a namespace will sever any link with the replication source or source DMA. Subsequent incremental updates will fail, requiring the source to re-establish replication. Failover should only be triggered when no further updates from the source are possible (as in a disaster scenario).

    Multiple namespaces can exist on the system at the same time. Active objects can exist in the system alongside namespaces without interfering with replication updates. VDBs and dSource within a namespace can also be used as a source when provisioning. For more information see the Provisioning">">Provisioning from a Replicated dSource or VDB topic.

    Failover and Conflict Resolution

    To activate the objects in a namespace, you must first fail over the namespace. This will sever replication and move the objects to the global namespace, where they can be manipulated in the same fashion as other objects on the system. Any active objects with conflicting names will cause an error at the time of failover. The error message will indicate which object(s) have conflicting names. The active objects must be renamed, since the namespace objects are read-only, before the failover operation can complete successfully.

    *Given that conflicting names prevent failover from succeeding, best practices in a disaster recovery situation are to leave the target system completely passive with no active objects until the time that a failover is required.

    Once a namespace is failed over, the objects are active but will be automatically disabled.