Backing up to Tape Streamer

The contents of this page apply only up to release 4.525/4.621, and are possibly best ignored for all releases incorporating the DYNABACK −COPY facility. For these releases the best way to back up a database to tape is first to use DYNABACK −COPY to backup and check the database, and then to use tape backup software to backup this copy. You should never use a tape backup utility to backup the real database files while they are in use, as if you restored such a backup it would almost certainly be corrupt.

The tape backup facility is directly available under most of the supported operating systems (on Windows Windows 3.1 you have to use an MS-DOS batch file). Before you use these steps, you will need to know how to write a batch file or shell script and include the commands necessary to back up to the tape streamer.

The advantages of using the DP4 tape backup facility to run the batch file rather than using the operating system are:

• A partial integrity check is performed on the database.
  
  
• You are prompted to backup the transaction log and it is deleted if you do.
  
  
• The session numbers for the database and transaction log are incremented.
  
  

You should create a batch file in the current directory, or in a directory that is included in your path, called:

• TAPEBKP.BAT for DOS, Windows and FlexOS
• TAPEBKP.CMD for OS/2
• tapebkp for UNIX
  
  

Include the instructions necessary to back up the database files from your workstation to the tape streamer you are using. To make the batch file generic to any database, use the variable %1 in place of the database name. DP4 will pass the name of your database to your batch file when you run the Database backup utility.

This is an example TAPEBKP.BAT batch file:

echo "Backing up to tape streamer on drive T:"
BACKUP %1.* T:\
echo "Database file copying complete"

1. On the DP4 System menu, select the Run program option.

2. Use this command to specify a tape backup:
   DBBACKUP -TAPE
   and press <Enter> to execute it.

3. Select the database name. The Database Backup utility screen is displayed.

4. Press <Enter> when you are ready to back up the database.

5. The Database Backup utility runs the batch file TAPEBKP.BAT. The database name is substituted in place of the variable %1 in the batch file.

6. DP4 asks you if the backup was successful.

   Answer 'No' to repeat the backup procedure. Answer 'Yes' to continue with the backup process.

7. If a log file is found, you are prompted to verify it:
   
   Answer 'Yes' to make sure the transaction log is written to disk correctly. Answer 'No' to skip the backup verification. Answer 'Abort' to return to the Database, Backup, Recovery and Check menu.
   DP4 calculates the database checksum. This is a partial check to help ensure that the database files are valid.

8. You are prompted to load a new disk for the log file. Once the log file is copied, DP4 prompts you to label the disk with the session number for the log.

The Database Backup utility terminates and you are returned to the DP4 System menu.