GSA Mirroring, or GSA^n, is simply the ability to link two or more appliances together so that they share the same configuration and search index. This article is an introduction to this powerful technique that should be in every search administrator’s toolkit.
The most common reason for mirroring is high availability. A mirror appliance can serve as a “hot spare” in case the primary appliance fails. With the help of a load balancer, mirrored appliances can even share the load with the primary appliance and increase the number of users who can search simultaneously.
Mirroring is also useful utility for migration. For example, you may need to replace your appliance. Simply add the new appliance as a mirror to configure it, then disable mirroring and remove the old appliance. Alternately you may be adding an appliance as a test or development environment. Make it a mirror to pick up the configuration, and then disable mirroring so that you can use each appliance separately.
Before you can start mirroring, there are a few prerequisites:
- The appliances must have the same software version and license count
- There must be a strong network connection between the appliances (sustainable 1 MB per second) with the correct ports open.
- You should backup configuration of both appliances by performing an configuration export.
- On the new replica, make sure to stop crawling, reset the index, and confirm that the index has cleared.
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The primary appliance is responsible for crawling and indexing content, and almost all configuration changes must be done on the primary appliance. Once mirrored, he mirrors are in constant communication, and the configuration changes and index data, and spelling data will be copied to each mirror. With GSA version 7.2, the Connector Manager definitions and configurations are copied as well.
There are a configuration items that must be configured separately on the replica. These are:
- Connectors (Connector Manager definitions and configurations are copied)
- Existing feeds
To learn more, refer to Google’s comprehensive GSA Documentation for Configuring GSA Mirroring. In addition, the GSA Administrative Help for mirroring can be found here or through the help link on the GSA administrative console.