Starting a continuous logical-log file backup

When you do not want to monitor the logical-log files and start backups when the logical-log files become full, you can start a continuous backup.

About this task

When you start a continuous backup, the database server automatically backs up each logical-log file as it becomes full. When you perform continuous logical-log file backups, the database server protects you against ever losing more than a partial logical-log file, even in the worst case media failure when a chunk that contains logical-log files fails.

To start a continuous backup of the logical-log files, use the ontape -c command. The -c option initiates continuous backup of logical-log files. The database server backs up each logical-log file as it becomes full. Continuous backup does not back up the current logical-log file. The database server can operate in online mode when you start continuous backups.

Whether the logical-log files are backed up to tapes or a directory depends on the setting of the LTAPEDEV configuration parameter:

  • If the LTAPEDEV configuration parameter is set to a tape device, someone must always make media available for the backup process. When the specified mounted tape becomes full before the end of the logical-log file, the database server prompts the operator for a new tape. Also, you must dedicate the backup device to the backup process.
  • If the LTAPEDEV configuration parameter is set to a directory, logical-log files can be backed up unattended. Logical logs are backed up as they fill and a new file is created in the directory for each logical log. Backup is limited by space available for new files.

To back up to a directory, as an alternative to using the ontape -c command, you can call the ontape -a -d automatic logical log backup command from a script specified by the ALARMPROGRAM configuration parameter. You can use either the alarmprogram or script or the log_full script, both of which are found in the $INFORMIXDIR/etc directory.

Procedure

To use the alarmprogram script to back up logical logs to a directory:
  1. Set the LTAPEDEV parameter to an existing directory.
    Make sure that this directory is owned by informix and group informix.
  2. Edit the ALARMPROGRAM script ($INFORMIXDIR/etc/alarmprogram.sh on UNIX™ or Linux™ or %INFORMIXDIR%\etc\alarmprogram.bat on Windows™), as follows:
    1. Set the BACKUPLOGS parameter within the file to Y.
    2. Change the backup program from onbar -b -l to ontape -a -d.
  3. Restart the database server.