Peer DRS Backup & Restore Process

Peer DRS uses a form of log shipping as it's methodology for replication, and in order to understand how Peer DRS works, you need to understand how log shipping in general works. With log shipping, proximity is not a limitation; you can place a standby server in a geographically remote location to protect against a catastrophic disaster. Log shipping is a high-availability technique that allows you to bring a standby database online in case the primary database encounters problems, or if you want to perform scheduled maintenance on the primary server. Replication can be used to distribute load across multiple servers, move data from a central server to remote servers, or combine data from multiple sources into a single location.

A Full Backup of the database is taken on the primary server and stored in a Backup Folder located either on the primary server, or more than likely, a network shared drive accessible by the domain user account that the Peer DRS application is run under. The files in this Backup Folder can also serve as your backup archives.

2.	Full Backup File Copy: If the target copy destination folder is different than the Backup Folder, the files are copied to the destination folder of all configured targets, otherwise no copy is performed.

Full Target Restore: The full backup files are restored into the target standby server. The target database is not operational; but if supported by the replication module, the database can stay in read-only warm standby mode. Currently, only the MS SQL Server replication module supports this feature.

4.	Based on the configured incremental backup schedule (e.g. every 15 minutes), incremental changes are recorded in transaction log files and stored in the shared Backup Folder

5.	Transaction log backup files are copied to all configured target database destination folders immediately after an incremental backup of the primary database is performed.

6.	Transaction log backups are restored to the target database on the target server in the order that they were taken on the primary server.

Below is a diagram illustrating the Peer DRS log shipping methodology. The illustration shows Peer DRS installed on a separate server from any of the databases; however, you can also install Peer DRS on the same server as the primary database or on any of the target database servers. If Peer DRS is installed locally on either the primary or target database servers, then some of the network shares may not be necessary.

Note: The MS Exchange Server replication module's backup and restore process works slightly different and details can be found in the Exchange Backup & Restore Process section.