Configuring Index Replication

Owned by Heather Geyer
Apr 21, 2022
3 min read

Voyager software supports replication of indexes to improve reliability, fault tolerance, and accessibility. It uses a master/slave model for replication where slave indexes are copies of a single master index. The slave instances poll the master index at a user-defined interval and copy the master index to the slave index. You can configure one or more slave instances to replicate a single master index.


Replication differs from Federated Searches, where the master index is a super-set of the remote indexes.  Federated Searches distribute the indexing tasks, while Replication distributes the same index to subsidiary indexes.

To configure a master/slave deployment, start with two separate instances of Voyager and set their respective instance replication modes to MASTER and SLAVE.

To configure the master instance:

  1. Go to Manage > Index > Replication

  2. Change the Mode from Disabled to MASTER

  3. Click Save

  4. Restart the Voyager Master instance to apply the changes

IMPORTANT 
The master instance must contain at least one location (in Manage > Voyager > Discovery > Locations) and an its index must contain one or more records before you can replicate content to the slave instance(s).

To configure the slave instance:

  1. Go to Manage > Index > Replication

  2. Set the Mode to SLAVE

  3. Specify the URL to the MASTER Solr index - typically http://<server>:port/solr/v0/replication

  4. Define the polling interval in the format HH:MM:SS

  5. Click Save

  6. Restart the slave instance to reflect the changes

  7. Repeat these steps for any additional slave instances you want to link to the master

Once you have configured Voyager replication and set up the master and slave instance,:

  • The contents of the master index are replicated to the slave index. 

  • Any changes made to the master index (records added or deleted) are replicated to the slave index. 

  • If the Voyager master instance indexes new content, the indexed records are replicated at the polling interval. The index replication occurs at the rate of file transfer between instances. If the full replication transfer takes longer than the polling interval, any remaining content in the index continues replication during the next polling interval event. This process continues until the index is completely replicated.

IMPORTANT
When you are configuring replication, make sure that:

  • The slave index does not index any content itself, otherwise the slave index will be erased and overwritten by the master index at each replication interval. That means that there should not be any additional locations listed at Manage Voyager > Discovery > Locations.

  • The replication polling interval is not shorter than the most frequent Voyager location scheduled indexing tasks. 

  • If either the master or slave index is not running at the time of the index polling, replication will not occur.

For More Information
You can refer to the Solr index page for additional information on the replication settings, the index, and the index iterations.

To access the Solr index page:

Go to Manage > Index and click the Manage Solr link.
—or—
Go directly to http://<server>:<port>/manage/index/solr/#/v0/replication

From the Solr index page, choose Core Admin (a), index v0 (b) and Replication (c). The following image shows the Voyager slave, Solr index page.