Restore Points add significant value to the Dynamic Dump hot backup feature and long term backup maintenance.
To reduce the overhead of Dynamic Dumps, especially when the Dynamic Dumps are run routinely to provide a backup mechanism, the Restore Point feature allows a single Dynamic Dump to be followed by RPs, eliminating the need for additional Dynamic Dumps.
The RP capability introduced support for two types of RPs:
When a Checkpoint Restore Point is created, a Restore Point file is created. This file is very similar to a start file except that it points to the log position of the RP instead of a checkpoint. For more about the file, see Restore Point Files.
Without Restore Points, the ctfdmp utility updates c-tree files starting from a checkpoint in the transaction log that has no active transactions, and continues executing until all the subsequent transaction log entries have been processed. Typically, the starting point for the ctfdmp is specified by the start file that the Dynamic Dump restore (ctrdmp) creates.
Checkpoint Restore Points provide a safe, well-defined position in the transaction log where ctfdmp can terminate. It can then be restarted at this same location (using the Restore Point to create a start file), and run until another Checkpoint Restore Point, and so on. Hence an "incremental roll forward" ability.
Don't use superfiles with incremental roll forward. Superfiles are OK with Dynamic Dump, restore, and a single roll forward. Due to how superfiles store offsets, incremental roll forwards with superfiles could cause a problem. Keep in mind that FAIRCOM.FCS is a superfile, so we recommend omitting this file if you are performing incremental roll forward operations.
Incremental Roll Forward Strategy
Primary Server System Maintenance
Backup Server System Maintenance
In the event your primary server is shut down or crashes and it is desired to switch to the backup server, it will be necessary to run ctfdmp from the last restore point until the end of the existing log entries. c-tree files are then available on the backup server ready to be used as your now primary server.
Manually Creating a Point-In-Time Forward Roll
A forward roll can only be started from a checkpoint and not from an arbitrary point in time reached with a rollback operation. Furthermore, the checkpoint must be created when the following conditions are true:
This means that a forward roll requires more than just a starting checkpoint: the state of the data and index files must correspond to the current state of the transaction logs and the position of the starting checkpoint. To roll forward, you will need to have saved a point-in-time copy of the data files, index files, transaction logs, and transaction start files. There are several methods to generate a forward roll eligible backup: