Cisco CRS-1 - Carrier Routing System Router Administration Manual page 276

About the CRS Datastore
The publisher is the main database. All data is written to this database, with the
other databases (subscribers) synchronizing with the publisher. If the publisher
fails, then data can be written to the subscriber(s). When the publisher is back
online, it returns to accepting writes. It also synchronizes with the subscriber(s)
by:
•
•
•
When the publisher is fully synchronized, then all subscribers return to
synchronizing with the publisher.
Note You cannot deactivate publisher datastore components. To deactivate a publisher
datastore component, first change the component to be a subscriber and then
activate the component (see
Internally, CRS datastores use the Microsoft SQL Server merge replication
model. This means that a publisher is associated with a snapshot agent and a
subscriber is associated with a subscription agent.
•
•
New nodes added to the cluster having datastores that use replication will at first
not have any replication role or type. Once the datastore component is activated
from the Control Center, it will act as a subscriber by default. A subscriber will
be effective only when a publisher is activated; any subscriber node can become
a publisher.
This means a datastore with replication can play the following roles:
1.
2.
Cisco Customer Response Solutions Administration Guide, Release 4.1(1)
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Adding any files or records that are new.
Deleting any files or records that have been removed.
Updating any files or records that have a later modification stamp on the
subscriber database.
Snapshot agent. Generates a snapshot or image of the current database data.
For the CRS datastores, usually a new snapshot is generated only when the
publisher is created or a subscriber is added. However, the CRS administrator
has the option of manually triggering a snapshot.
Subscription agent. Actively replicates data between the publisher and
subscriber. Since CRS uses bidirectional replication, the subscription agent
will replicate data from publisher to subscriber as well as from the subscriber
to the publisher.
Unknown/Deactivated
Subscriber
Chapter 9
Changing Publisher to Subscriber, page
Managing the Cisco CRS Datastores
9-8).