Automatic Database Backup and Rollforward Recovery

The recommended method of using Fileshare's update logging for rollforward recovery is:

  1. Periodically to shut down the Fileshare Server
  2. Take a backup of all your database files
  3. Re-start the Fileshare Server with a fresh recovery log file

See the section Rollforward Recovery Logging for further details.

You can get Fileshare to do this for you automatically by specifiying a backup directory-name in the database reference file using the /backup option. For example, the command:

fs /d dbase.ref /backup	c:\backdir

adds an entry to the database reference file called dbase.ref which specifies the backup directory as c:\backdir. A full path can be specified for the backup directory, otherwise paths which are not fully qualified are taken to be relative to the current directory of the Fileshare Server.

Setting a backup directory in this way causes the Fileshare Server to copy all the data files specified in the database reference file to the directory c:\backdir or /backdir on startup. The Fileshare Server also deletes any recovery log file(s) that it finds since this data is obsolete once the database files have been backed up.

While the Fileshare Server is active, all updates to files which have logging switched on for them are recorded in the log file as normal. The next time the Fileshare Server is restarted, it backs up the database files again and discards any log file(s). However, if it detects that the previous Fileshare Server session did not shut down successfully and a valid terminating record had not been written to the log file (for example, as a result of a system crash), then Fileshare automatically triggers the Rollforward Recovery Utility. This automatically restores the previous backup of the database files and recovers all updates to them as recorded in the log file(s). If the recovery completes succesfully, the Fileshare Server starts up as normal.

It is still possible to run the Rollforward Recovery Utility manually before starting up the Fileshare Server when a backup directory is specified in the database reference file. The Rollforward Recovery Utility automatically restores the previous backup before initiating the recovery.

Note:

The purpose of the automatic database backup facility is to help database administrators follow the recommended steps for rollforward recovery, thus ensuring that the latest Fileshare log file contains only the updates made since the last database backup. If database files are added or replaced manually, Fileshare may not detect this and could backup or restore the incorrect version of a file, compromising the integrity of your data. We recommend, therefore, that you do not attempt to replace any of the database files manually and only ever use Fileshare operations such as closing down the server to back up the entire database.

If you have enabled automatic database backup by specifying a backup directory, you cannot use the "/o l" option to switch logging off for any of the data files declared in the database reference file. By having logging active for every file specified in the database reference file, Fileshare can guarantee that it can recover updates to them all when it copies backed-up versions from the backup directory. If there are some files for which you do not require automatic backup, omit them from the database reference file.

If you need to back up your Fileshare files, for example as part of a system-wide backup overnight, you can use a Fileshare Manager API function to request Fileshare to shut down, back up all the database files and then restart with a fresh log file. Having done this, we recommend that you then make a permanent hard copy of the Fileshare backup directory. See the section Fileshare Manager in the chapter Advanced Operation for more information.

Example

fs /d dbase.ref /l logfile
fs /d dbase.ref /backup c:\backdir
fs /d dbase.ref /f c:\accounts\customer.dat 
fs /d dbase.ref /f c:\finance\history.dat


These commands perform the following:

  • Create a database reference file called dbase.ref
  • Specify the recovery log file as logfile so that the first log file that the Fileshare Server creates is called logfile.L01
  • Specify that any updates to the files c:\accounts\customer.dat and c:\finance\history.dat are logged
  • Specify c:\backdir as the backup directory

On startup, the Fileshare Server automatically backs up these data files in the directory c:\backdir or /backdir. If the log file is backed-up while the Fileshare Server is active, backup files are also placed in this directory. If the Rollforward Recovery Utility is invoked, the backup files in c:\backdir or /backdir are restored to their original directories and any updates recorded in the log file(s) are re-applied.