Primary Database

A database that will be backed up and replicated to one or more target databases.

Primary Server

The server where a particular primary database resides.

Target Database

A database that was replicated from a primary database

Target Server

The server where a particular target database resides.

Replication Job

Stores configuration and job schedule information for replicating a single primary database to one or more target databases.  

Database Server Instance

A unique instance of database server software running on a physical machine.

Data Source

Stores connection information to a unique Database Server Instance (for Exchange this is a unique Storage Group Instance running on an Exchange Server).

Full Backup

A complete backup of all data in a primary database.

Incremental Backup

Contains only the data that has changed since the last full or incremental backup (which ever was last).

Differential Backup

Contains only the data that has changed since the last full backup.

Transaction Log

A physical file of updates performed on a database.

Backup Folder

The directory/folder that stores a primary database’s full backup and incremental transaction log files.

Target Copy Destination Folder

The folder/directory where files located in the Backup Folder are copied to before performing a restore on the target.  This folder must be accessible from the user/process the target database is running under.

File Copy Only Target

A Target that is configured to only copy a primary database’s backup files to a remote location without performing a restore.

Standby Target

A Target configured to copy a primary database's transaction files to a remote location and restore them into the target database acting as a standby server. You can use the standby database on the target server in place of the primary database if the primary server fails or must be taken offline for planned maintenance. The standby database is always slightly out of synchronization with the production database. You can control the level of synchronicity--it can be as short as a minute if a high-speed network is used, or as long as you choose.  In addition, standby target servers do not need to be identical to the primary server, although differences in the amount of memory, the number and speed of the processors, and the robustness of the storage system can affect database performance after a role change.

Continuous Replication

The process of continuously monitoring when a transaction log file is committed to disk and copy the file to the backup folder.

Log Replay

The process of playing transaction logs taken from the primary database to a target database.

Replication Module

A licensed Peer DRS Replication Module corresponding to a specific database platform e.g. MS SQL Server, MS Exchange Server, etc.

Database Role Change

The process of promoting a target standby server to assume the role of the primary server and demoting the original primary server to become a standby server.

Failover

Failover means substituting a primary server with a backup standby target server if the primary hardware becomes unusable.  Failover can also be used to provide close to 100% uptime during primary database or server maintenance and during software upgrades you could use the standby server to continue serving your users and applications.