Continuous data protection (CDP)
Continuous data protection (CDP) is a feature that continuously monitors the changes on a target server and backs up ongoing changes as soon as the changes are detected. It retains intermediate changes so you can recover data from a specific time.
CDP differs from a “point-in-time” backup and from replication or mirroring, which only keeps a snapshot of the latest image. You can enable CDP when creating or editing a backup. When CDP is enabled, the backup is triggered based on the detection of a change to a file on the backup source.
NOTE: Do not use CDP when performing an assisted delete, deleting a backup, or for disc/tape request operations.
CDP is available for the following backups:
• File system (Windows or Linux) – When configuring a File system backup with CDP, it is not necessary to select an entire server. You can select specific parts of a server, including any combination of share level, folder level, and file level filters. Extended regular expressions can be used to define complex selections.
NOTE: CDP supports pure file system backup items only. System Status and Services Database are not supported.
• Microsoft Exchange Server using EWS (Windows) – When configuring a Microsoft Exchange Server backup (EWS) with CDP, you can select user accounts or individuals folders within the user accounts. Selecting individual emails with CDP enabled is not recommended. When an individually selected email is removed from its original location, it is not backed up.
NOTE: When using CDP, the Use Buffer, Pre-Scan, and Follow Junction Point options are not supported.
Before using the CDP option, do the following:
• Consider the number of generations you want to maintain online. Normally, each change counts as a generation. The file change detection method depends on the operating system and backup kind. Backup frequency depends on the interval selected, which can be wide (up to many hours) or precise (down to the second-level).
• Ensure the system clocks on the DS-Client computer and the backup source computer are synchronized. CDP is a time-sensitive operation.
• For Microsoft Exchange Server (EWS) backups, ensure:
– Autodiscover has been enabled on the Microsoft Exchange Server and the address Autodiscover provides is resolvable.
– The internal network has a DNS server / hosts file configuration. This ensures the IP address of the Microsoft Exchange Server can be returned when the DS-Client attempts to connect to the Microsoft Exchange Server via the FQDN provided by the Autodiscover service.
After a CDP backup begins (on demand or scheduled), the session will continue to run unless explicitly stopped, for example, by the scheduled end time or by the user. The DS-Client continuously monitors the ongoing changes on the target backup server throughout the entire backup session.
As soon as the DS-Client detects a change, it immediately backs up the changes to the DS-System. On-demand and scheduled CDP backups use the reconnection settings from the DS-Client. CDP stops when one of the following events occurs:
• An on-demand stop is triggered.
• The scheduled time limit is reached.
• CDP is suspended by conflicting activities like, scheduled retention, validation, and BLM.
• CDP reaches the limit of retry connection attempts to the DS-System.
• Other unexpected stop conditions (exceptions, failed to connect to target, etc.)