Configuring Shadow Database

This topic describes the procedure to define or redefine a Shadow Database configuration, carried out by selecting option 1 on the tlmenu Configuration and Setup menu.

Other procedures on the Configuration and Setup menu are described in Configuring Transaction Logging.

Overview

Configuration of Shadow Database is carried out from the tlmenu Configuration and Setup menu, displayed by selecting option 2 on the main administration menu. Refer to tlmenu for an overview.

The first procedure, option 1 on the Configuration and Setup menu, is used to configure two Reality databases as a Shadow pair, configuring one as the 'live database' and the other as the 'Shadow Database'. It defines the following for each database:

Transaction Logging information
Live/Shadow roles

Having defined the Shadow Database configuration, you must then start logging on the live database by selecting option 2 on the Configuration and Setup menu. Refer to Starting and Stopping Logging and Configuring the Transaction Logging Status Monitor.

Each procedure, started by selecting a sub-menu option, comprises a sequence of message prompts to guide you through the process. Refer to Replies to Prompts for a description of the required responses.

Transaction Logging Menu System                 Wed   Sep  7 14:14:33 2005
Database name : dbase2                          Host name : payroll
State         : Transaction Handling/Logging not 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) :

Shadow Database Configuration and Setup Menu

Note: If you are using Database Isolation, both databases must be associated with the same instance of Reality.

Defining/Redefining a Shadow Database

Notes:

Before starting this procedure, ensure that you know the full pathname of the other database and clean log partition (directory) on your system.
Ensure that Transaction Logging is stopped on both databases.

This procedure must be carried out on both databases in the Shadow Database configuration before Shadow operation is fully configured. It performs the following:

Configures Transaction Logging on the database by creating the database's clean log sub-directory.
Configures the current database for Shadow operation by defining it as the live or Shadow Database, as necessary.

Procedure

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

You are asked to select the resilience option that you want to configure with the menu prompt:

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) :

Configuring Transaction Logging

Select option 3 to start to configure the database for Shadow Database operation.
The following prompt is displayed:
```
Enter the name of the Shadow pair: payroll (example)
```
This determines the name of the Shadow Database pair. On UNIX, a directory of this name is created in the directory /usr/realman/shadow, in this case payroll. On Windows, an entry of this name is created in the Registry.

If Transaction Logging is already configured, the following message prompt is displayed:
```
Transaction Logging already configured
Do you want to continue (y/n/q) ? :
```
Enter y to continue with re-defining Transaction Logging on the database.
If you are configuring Transaction Logging on a partition database, you are then prompted:
```
Do you wish to set up database for Rapid Recovery File System (y/n/q) ?:
```
Enter y to enable Rapid Recovery on this database, or n if you do not want to configure for Rapid Recovery. (Refer to Introduction to Rapid Recovery and Configuring Rapid Recovery for more information.)
You are now prompted to define/redefine the clean log directory name for the database, as follows:
```
Enter full path name of Clean Log directory (log_directory/n):
```
Enter the full clean log directory name. Entering n returns you to the Configuration and Setup menu. If you are re-configuring, any new clean log sub-directory you specify will overwrite the clean log sub-directory entry currently in the database config file.
You are then prompted for the name to be given to the clean log sub-directory to be used by the database.
```
OK to make Clean Log subdirectory sub_dir_name, (y/n/sub_dir_name):
```
Enter a name for the clean log sub-directory or enter y. Entering y assigns the default name, shown in the message prompt. Note that on UNIX the default is the database name and on Windows is the Shadow pair name.

If you enter a name instead of accepting the default, a clean log sub-directory is created with that name and you are prompted to confirm that it is correct.
```
OK to make Clean Log subdirectory new_name, (y/n/sub_dir_name) :
```
If the clean log sub-directory already exists, then you will see the message:
```
Clean Log subdirectory sub_dir_name already exists
Do you want to overwrite it (y/n/q) ? :
```
Enter y to continue the procedure using the selected clean log sub-directory name.
When you have set up the configuration parameters, the following message is displayed:
```
About to make Clean Log subdirectory database_name
in Clean Log directory clog_directory_name
for database database_path
Is this OK (y/n/q) ? :
```
Enter y to configure Transaction Logging with the parameters shown above. You are then returned to the Configuration and Setup menu.

Configuring the Shadow Pair

When you have configured Transaction Logging on the current database, the following prompt introduces the procedure to configure the database as one of a Shadow pair.
```
Is this a live or shadow database (l/s/n) ? : 
```
Enter l to configure the database as the live one, that is, the one to which users will log on to, or s to configure it as the Shadow.
Next you are prompted for the full path name of the other database in the Shadow pair.
```
Enter full path name of paired database (paired_database/n) : /real1/dbase1 (example)
```
Enter the full pathname of the other database.
tlmenu is now ready to configure the database for Shadow operation. However, it first asks for confirmation that the configuration parameters you have entered are correct. For example:
```
About to configure database "/real0/dbase0" as the "Live" database
paired with database "/real1/dbase1".
Is this OK (y/n/q) ? :
```
If you are happy with the configuration, enter y.
You are then asked:
```
Do you want to configure the shadow database now (y/n/q) ?:
```
Enter y to configure the Shadow Database, or n to quit the configuration procedure. On completion, press return to return to the Configuration and Setup menu.

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