The first time you do a backup check the downloaded file to be sure it is not a 0k or 1k file. If the file is empty, the dump command did not work. The most likely reason for it not working is an invalid path in configuration settings for the mysqldump command.
Windows server users: you may experience difficulty getting the backup to work even if you have the correct path to mysqldump in the configuration setting. Your best source of information will be your web host’s technical support department. You might also read the PHP manual for the system() function (which is used to excute the mysqldump command). Do a series of finds on that page for "windows" to read what others have experienced.
Tip: Create a bookmark that points to http://yoursite.com/talkbak-path/admin/?action=backupdb. This eliminates the need to go to the admin maintenance menu to backup your database.
Backing up your comments database on a regular basis is important. You will kick yourself if your server crashes and loses your comments and you don’t have a very recent backup.
After clicking the backup button, the data will be gathered into a file. When that is finished you will be prompted with a standard download dialog to save the file on your PC. After it is saved you can delete the prior backup file from your PC.
The backup routine uses the standard mysqldump command. Use phpMyAdmin to restore the file.
To view the contents of the backup file, unzip it and open it in any text editor.
Note: The backup script also optimizes the database and clears the user_agent field in the comments table for comments older than user_agent_days. This removes up to 255 characters per comment from the database. It then optimizes the database before creating the backup.