Configuring Rapid Recovery

This topic describes the procedures carried out from the tlmenu Configuration and Setup menu to configure Rapid Recovery on a Reality database.

Overview

To use Rapid Recovery on a particular database it must first be configured. This is carried out from the tlmenu Configuration and Setup menu, displayed by selecting option 2 on the main Administration Options menu. Refer to tlmenu for an overview.

At the Configuration and Setup menu, select option 1 to initiate the procedure to configure the database for Rapid Recovery.

Transaction Logging Menu System                 Wed   Sep  7 14:14:33 2005
Database name : dbase2                          Host name : crime
State         : Transaction Handling/Logging enabled
        Configuration and Setup
        =======================

        1.  Define/Redefine the Database Configuration
        2.  Start Transaction Handling/Logging
        3.  Stop Transaction Handling/Logging
        4.  Configure the Transaction Logging Status Monitor
        5.  Configure backup method

        Enter option (1-5) :

Transaction Logging Configuration and Setup Menu

Setting Up a Database for Rapid Recovery

  1. Select option 1 on the Configuration and Setup menu. A message is then displayed describing the purpose of the procedure and prompting you to confirm that you wish to continue. Enter y  at the confirmation prompt.

  2. You are asked to select the resilience option that you want to configure, from the menu:

    Configure database for :
        1. Transaction Handling
        2. Stand-Alone Transaction Logging
        3. Shadow
        4. FailSafe/Heartbeat (Heartbeat on UNIX Only)
        5  Stand-Alone Rapid Recovery
        Enter option (1-5) :

    Either:

    • Select option 2 to configure both Rapid Recovery and Transaction Logging. When prompted:

      Do you wish to set up database for Rapid Recovery File System? (y/n/q) ?

      Enter y  and follow the procedure for Configuring a Database for Transaction Logging.

    Or:

    • Select option 5 to configure Rapid Recovery only. A message is displayed indicating that this will also enable Transaction Handling; enter y to confirm that you want to continue. Rapid Recovery is enabled on the database and you are then returned to the Configuration and Setup menu.

    Note

    Transaction Handling must be running in order for Rapid Recovery to be possible. If logging is stopped on the database — either by executing TL-STOP at TCL or via option 3 on the tlmenuConfiguration and Setup menu — the Rapid Recovery feature is inhibited. It will not be possible to recover the database following a system failure until Transaction Handling is restarted.

Recoverable Files

When a database is configured for Rapid Recovery with Transaction Logging, individual files can have three levels of resilience:

Logged files (marked DL in their file definition item) have all updates logged in a clean log for auditing and disaster recovery purposes. These files are fully recoverable after a system crash. This mode should be used for main data files.

Note

Recoverable files (marked DR in their file definition item) have recent updates logged on the raw log only. These files are fully recoverable after a system crash. This mode can be used for files that are derived from main data files, for example, application level indexes. When you create an index with the CREATE-INDEX command, it is automatically set to be Recoverable.

Recoverable files are not transferred to a Failsafe secondary and hence should not be used in a Failsafe pair.

Scratch files(marked D in their file definition item) have only recent structural changes recorded in the raw log. After recovery, these files will be structurally intact but may not contain valid data. This mode can be used for scratch files, which are typically cleared when a user logs on.

When a database is configured for Rapid Recovery without Transaction Logging, individual files have two levels of resilience:

Recoverable files(marked DL or DR in their file definition item) have recent updates logged on the raw log only. These files are fully recoverable after a system crash.

Scratch files(marked D in their file definition item) only have recent structural changes recorded in the raw log. After recovery, these files will be structurally intact but may not contain valid data. This mode can be used for scratch files, which are typically cleared when a user logs on.

To set the logging status of files, use the TL-SET-LOG-STATUS command.