Dell DX6004S Setup And Configuration Manual - Page 28

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Dell DX6004S Setup And Configuration Manual
Chapter 6. Support for Content Restoration and Fail-
Over
Some common uses of DX Content Router are disaster recovery, backup, and archiving. In all these
cases, it will sometimes be necessary to recover lost content data from a remote cluster. The exact
nature of such a recovery process, and the ease and speed with which it happens, will depend
somewhat on the topology of the cluster network.

6.1. Administrative Disaster Recovery

If the topology involves a one-way connection between the primary and DR clusters, then recovering
from a disaster that causes loss of data, perhaps because one or more nodes in the primary cluster
have been destroyed, must involve an administrative process to reverse the data flow. That's
because the primary cluster in such a topology is running only a Publisher service, which moves
data from the primary to the DR. In order to move data in the other direction for recovery purposes,
the primary cluster (and perhaps also the DR cluster) will need to be reconfigured to run one or
more Replicators, allowing the DR site to reconstitute lost data in the primary. Any lost data will be
unavailable until the loss is discovered and corrected by the two Content Router nodes.
Note
Administrators who temporarily install a Replicator or Publisher service on a DX Content
Router node as part of a DR event should plan to uninstall the temporary service when
all of the original objects have been replicated back to the source cluster. Failure to do so
may result in unintentional creation of a mirrored configuration when the cluster returns to
normal since both services will be installed on the same server.

6.2. Content Mirroring

In a mirrored architecture where the primary and DR clusters are both running paired Publishers
and Subscribers, the DX Content Router nodes will ensure that all appropriate data exists in both
clusters at all times. If there is a disaster in the primary cluster, the data can be repopulated using
the "Republish" function in the DR Publisher admin console.

6.3. Application-Assisted Fail-Over

In both the above scenarios, the loss of data can be corrected, but will be unavailable to applications
in the primary cluster until the DX Content Router nodes do their jobs and recover the data. If these
applications are made aware of the presence and address of the remote DR cluster, and if they
have visibility and access to the remote, then the applications can automatically fail-over to the
remote cluster in the event a stream is not currently accessible in the primary.
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Version 2.2
December 2010