Restore point

Restore points are used to restore an old system state if TwinCAT/BSD exhibits undesirable behavior after a major system change or misconfiguration, and this behavior is not easy to rectify. The advantage of restore points is that these configuration errors are easily and quickly undone without reinstalling TwinCAT/BSD.

You define the time to create a restore point, for example, when you make a larger system change or install third-party programs. However, restore points are not a substitute for a full backup and do not protect against data loss. Regular backups are another protection measure that allows you to protect yourself from data loss due to defective storage media, for example (see: Creating a backup).

The restore points are created and managed in the console using the restorepoint program. The following modes are supported by the program:

• status: Lists all available restore points. On delivery, a restore point named factoryreset, the Beckhoff factory settings, is available.
• create: Creates a new restore point. The name of the restore point can be set as an argument. If no name is specified, an automatically generated name is used.
• rollback: Return to a specific restore point. Note that all data created after the restore point will be destroyed. If no restore point is specified as an argument, the user is asked with an interactive dialog.
• destroy: The specified restore point is destroyed. In this mode, all existing data is preserved, but the restore point itself is deleted.

Restore points under TwinCAT/BSD are based on ZFS snapshots. As a result, they consume very little memory when they are created. Any change in the saved restore point for the current live system the user is working with is reflected in the memory space used by the restore point. Use zfs list -t snap to display all system snapshots.

The USED column shows the actual space used by the snapshot; the REFER column shows the space referenced by the snapshot but actually stored in other datasets. It is therefore always advisable to create a restore point before making any changes in the system, since this hardly uses any system resources. After some time and many changes between the restore point and the live system, it is recommended to delete restore points that are no longer needed in order to free up the increasing memory space used by the restore points.