## 5.4 Configuration Parameters
Use the following parameters to prepare your system for secondary time travel.
The parameters are defined in the system\_replication section of the INI file. All parameters are set on the secondary system.
| Parame­ ter   | timetravel_max_retention_time                                                                                                                                                           |
|--------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| Type         | integer                                                                                                                                                                                 |
| Unit         | minutes                                                                                                                                                                                 |
| Default      | 0                                                                                                                                                                                       |
| Descrip­ tion | If set to 0, secondary time travel is turned off. If this parameter is set to a value different from 0, the secondary system can be brought online up to the defined point in the past. |
| Parame­ ter   | timetravel_snapshot_creation_interval                                                                                                                                                   |
| Type         | integer                                                                                                                                                                                 |
| Parame­ ter   | timetravel_snapshot_creation_interval                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |
|--------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| Unit         | minutes                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
| Default      | 1440                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |
| Descrip­ tion | Defines how frequently snapshots are created for secondary time travel. Time travel snapshots are kept until they get older than the defined timetravel_max_retention_time parameter. If time travel needs to be done on an older point in time, the snapshot that best fits the requested point in time will be opened and the remaining changes are applied via log replay. A new snapshot is created when the point in time defined in this parameter has passed since the last snapshot creation. Snapshots older than the point in time defined in time_travel_max_retention_time are dropped. |
| Parame­ ter   | timetravel_call_takeover_hooks                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |
| Type         | bool                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |
| Values       | true, false                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
| Default      | false                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |
| Descrip­ tion | Indicates if takeover hooks should be called during secondary time travel.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
| Parame­ ter   | timetravel_logreplay_mode                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |
| Type         | enum                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |
| Values       | auto, manual                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |
| Default      | auto                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |
| Descrip­ tion | Defines how the log replay is executed on the secondary system. The following settings are allowed:                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
|              | ● Auto The log replay is done automatically up to the newest possible log position. ● Manual You must manually trigger the log replay up to the requested timestamp using the                                                                                                                                                                                                                                                                                                                                                                                                                       |
|              | -sr_recoveruntil hdbnsutil command.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |