Description

   The SET FILE/AI_JOURNAL command marks one or more RMS files
   for after-image journaling. You can also specify certain
   characteristics of the journal with this command, including its
   file specification, whether it is to be created, its initial
   size, and its default extension quantity. The SET FILE/NOAI_
   JOURNAL command unmarks a file for after-image journaling. After
   a data file is marked for after-image journaling with the SET
   FILE/AI_JOURNAL command, the following events occur whenever the
   file is opened by RMS for write operations:

   o  The journal is opened.

   o  All subsequent modifications to the data file are recorded in
      the journal.

                                  NOTE

      To be able to recover the data file at a later time,
      you must make a backup copy of the data file, even if it
      contains no data.

   You must use the FILE keyword to specify a journal. By default,
   any portions of the file specification that you omit will be the
   same as the data file that is to be journaled, but with the file
   type RMS$JOURNAL. That is, if you issue the following command,
   then, by default, the file specification for the after-image
   journal is JOURNAL_DISK:PAYROLL.RMS$JOURNAL:

   $ SET FILE/AI_JOURNAL=(FILE=JOURNAL_DISK:) FINANCE_DISK:PAYROLL.DAT

   You should always keep the journal for after-image applications
   on a different volume from that of your data file. If recovery
   becomes necessary, you will be able to perform after-image
   recovery only if a backup copy of the data file is available.
   Use the FILE keyword to specify the journal location.

   Use the SET FILE/NOAI_JOURNAL command to unmark a file for after-
   image journaling. After you use the SET FILE/NOAI_JOURNAL command
   for a file, modifications to that data file will no longer be
   written to the journal.

   You must use the SET FILE/NOAI_JOURNAL command before you can
   delete a file that has been marked for after-image journaling.