Replicas

You can make a database available to users in differentlocations, on different networks, or in different time zones, by creatingreplicas of the database.

All replicas share a replica ID which is assigned when the databaseis first created. The file names of two replicas can be different,and each replica can contain different documents or have a differentdatabase design; however, if their replica IDs are identical, replicationcan occur between them.

As users add, edit, and delete documents in different replicasof a database, the content in the replicas is no longer identical.To ensure that the content in all replicas remains synchronized, youuse Connection documents to schedule replication between the serversthat store the replicas. Then multiple sites, teams, and users canmake changes to a database and share those changes with everyone elsewho has access to that database. In addition, using replicas and schedulingreplication reduces network traffic. Users never need to connect toa single central server that stores the only replica of a particulardatabase. Instead, they can access a replica of that database on oneor more local servers.

These distributed replicas can also be Web sites that are hostedon differentDomino® servers.Then users aren't dependent on one server when they attempt to accesscritical applications over the Internet. If one server is unavailable,users can access another replica of the database on another server.You can also use replicas to help manage ongoing Web site design.On one server, you can set up a Web staging area where you designand test new pages. When the design changes are tested and ready tobe released, you can replicate this server with the server storingthe replica of the Web site that is available to users. By using replicasand replication this way, you prevent Web users from seeing your "work-in-progress."

A replica of a database isn't the same as a copy of a databasethat you make by choosingFile >Application >New Copy. Although a copy of a database may look the same asthe original database, a copy doesn't share a replica ID with theoriginal database and so it can't replicate with it.

Decidingwhen to create a replica

Plan your replica strategy carefully,and create replicas on servers only when necessary. The more replicas,the greater the demand on server and network resources and the greaterthe need for additional maintenance. To prevent unnecessary proliferationof replicas, assign Create Replica server access to only a few administrators.Then tell users and application developers to send their requestsfor new replicas to these administrators.

Create a replicaof a database to:

Keep in mind that two replicas will contain slightly differentcontent between replications. If users need access to the most up-to-dateinformation in a database, you can create replicas on clustered serversand then set up replication in clusters. In a cluster, all replicasare always identical because each change immediately replicates toother servers in the cluster.