Keywords

   Four keywords are used as parameters to the SET FILE/AI_JOURNAL
   command: ALLOCATION, [NO]CREATE, EXTENSION, and FILE. You must
   always use the FILE keyword; you can also use any, all, or none
   of the other three keywords.

   Use an equal sign (=)  immediately after the SET FILE/AI_JOURNAL
   command to use a keyword. If you use more than one of the
   keywords, enclose the list in parentheses and separate the items
   in the list with commas.


ALLOCATION=n

   Specifies the initial size, in blocks, of the journal. The
   ALLOCATION keyword is meaningful only when the CREATE keyword
   is also used.

   The default allocation is 0 blocks.


CREATE

   Specifies that a new journal is to be created. If no journal
   exists, using this keyword creates a new one. If a journal (with
   the file specification given in this command) already exists,
   using this keyword creates a new version of the journal. In the
   latter instance, the data file named in this SET FILE command
   is journaled to the new journal. Any other files that are being
   journaled to the previous version of the journal will continue to
   be journaled to that previous version.

   If a journal does not already exist, be sure to use the CREATE
   keyword with the SET FILE/AI_JOURNAL command. If you do not
   specify the CREATE keyword and the file that you specify with
   the FILE keyword does not exist, a journal will not automatically
   be created and an error message is displayed.

   When you create a journal for after-image journaling, the file
   protection for the journal is determined as follows:

   o  If a version of the journal that you specify with the CREATE
      keyword already exists, then the new version of the journal
      has the same file protection and access control list (ACL) as
      the most recent version.

   o  If there is no existing journal (that is, if you are creating
      version 1 of the journal), then the file protection and
      ACL of the journal are the default file protection for the
      process that creates the journal, except that none of the four
      ownership categories (system, owner, group, world) is given
      delete access.

   Also, every time that you use the CREATE keyword, be sure to make
   a backup copy of the data file. (If it is the first time that
   the data file is marked for after-image journaling, then you must
   make a backup copy of the data file, regardless of whether the
   CREATE keyword is used.)

                                  NOTE

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

   In most cases (in particular, when you are using after-image
   journaling to protect against loss of data from a device
   failure), you should keep the backup copy on a different volume
   from the 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.

   If you want to use a single journal for both after-image and
   before-image journaling, do not use the CREATE keyword with both
   the /AI_JOURNAL and /BI_JOURNAL qualifiers, because that will
   create two separate journals. When you create a journal that
   will be used for more than one data file or more than one type
   of journaling (after-image or before-image), you should first
   use a SET FILE command to create the journal for a single type
   of journaling and for a single data file. After the journal is
   created, then you can use a single SET FILE command for multiple
   data files and both after-image and before-image journaling. For
   example, you might use the following sequence of commands:

   $ SET FILE/AI_JOURNAL=(FILE=JNL_DISK:,CREATE) [WEEKLY]SALES.DAT
   $ SET FILE/BI_JOURNAL=(FILE=JNL_DISK:[WEEKLY]SALES) -
   _$INVOICES.DAT,COMMISSIONS.DAT


EXTENSION=n

   Specifies the default extension quantity, in blocks, for the
   journal. You can specify a value from 0 to 65,535.

   The EXTENSION keyword is meaningful only when you use the CREATE
   keyword. If the file is extended, the value that you specify is
   used. If you do not use the EXTENSION keyword when you create a
   journal, RMS calculates its own EXTENSION value for the journal.


FILE=journal-filespec

   Specifies the journal where all modifications to the named data
   file will be recorded. The default file specification for the
   journal is the file specification of the data file that you name,
   but with a file type of RMS$JOURNAL. If you provide a partial
   file specification for the journal, any unspecified portions are
   taken from the default file specification. The FILE keyword is
   required when you use the SET FILE/AI_JOURNAL command.

   If you are using after-image journaling to protect against the
   loss of data due to a device failure (such as a head crash),
   you should keep the journal on a different volume from the
   one on which the data file is kept. Only by keeping the data
   file and journals on separate volumes can you use after-image
   recovery to restore the data file if its recording medium becomes
   corrupted (for example, by a disk head crash). If you issue the
   SET FILE/AI_JOURNAL command and the journal is on the same volume
   as the data file being marked for after-image journaling, the
   INVAIJDEV warning message is issued.

   The file specification cannot include a node name, since the SET
   FILE command is not valid for network access.

   You can use a single journal for multiple data files for after-
   image journaling, and you can also use a single journal for both
   after-image and before-image journaling.