CCR and public folder replication are two very different forms of replication built into Exchange. Due to interoperability limitations between continuous replication and public folder replication, if more than one Mailbox server in the Exchange organization has a public folder database, public folder replication is enabled and public folder databases should not be hosted in CCR environments.

The following are the recommended configurations for using public folder databases and CCR in your Exchange organization:

• If you have a single Mailbox server in your Exchange organization and that Mailbox server is a clustered mailbox server in a CCR environment, the Mailbox server can host a public folder database. In this configuration, there is a single public folder database in the Exchange organization. Thus, public folder replication is disabled. In this scenario, public folder database redundancy is achieved using CCR; CCR maintains two copies of your public folder database.
  
• If you have multiple Mailbox servers you can host a public folder database in a CCR environment provided that there is only one public folder database in the entire Exchange organization. In this scenario, public folder database redundancy is also achieved by using CCR. In this configuration, there is a single public folder database in the Exchange organization. Thus, public folder replication is disabled.
  
• If you are migrating public folder data into a CCR environment, you can use public folder replication to move the contents of a public folder database from a stand-alone Mailbox server or a clustered mailbox server in an SCC to a clustered mailbox server in a CCR environment. After you create the public folder database in a CCR environment, the additional public folder databases should only be present until your public folder data has fully replicated to the CCR environment. When replication has completed successfully, all public folder databases outside of the CCR environment should be removed, and you should not host any other public folder databases in the Exchange organization.
  
• If you are migrating public folder data out of a CCR environment, you can use public folder replication to move the contents of a public folder database from a clustered mailbox server in a CCR environment to a stand-alone Mailbox server or a clustered mailbox server in an SCC. After you create the additional public folder database outside of the CCR environment, the public folder database in the CCR environment should only be present until your public folder data has fully replicated to the additional public folder databases. When replication has completed successfully, all public folder databases inside of all CCR environments should be removed and all subsequent public folder databases should not be hosted in storage groups that are enabled for continuous replication.
  

During any period where more than one public folder database exists in the Exchange organization and one or more public folder databases are hosted in a CCR environment (such as the migration scenarios described previously), consider the differences in behavior for scheduled (Lossless) and unscheduled (lossy) outages:

• If a successful scheduled Lossless outage occurs, the public folder database will come online and public folder replication should continue as expected.
  
• If an unscheduled outage occurs, the public folder database will not come online until the original server is available and all logs for the storage group hosting the public folder database are available. If any data is lost as a result of the outage, CCR will not allow the public folder database to come online when public folder replication is enabled. In this event, the original node must be brought online to ensure no data loss, or the public folder database must be re-created on the clustered mailbox server in the CCR environment and its content must be recovered using public folder replication from public folder databases that are outside the CCR environment.