ROLL FORWARD RECOVERY PROCESS
 This is a MicroFocus Feature
The following information comes directly from MicroFocus
Documentation and gives you a more detailed view as to how the
ROLL FORWARD process works.
Rollforward Recovery Utility
The Rollforward Recovery Utility enables you to recover updates to data files after a
system failure. However, before you can recover a data file, the name of the data file
must have been entered in the database reference file, and the database reference file
must have had a log file name entry. When the Fileshare Server was running, these entries
in the database reference file caused updates to the required data files to be stored in
the rollforward recovery log file before attempting the rollforward recovery process, all
of the recovery log files created when the Fileshare Server was active should be in the
recovery log file directory (or log file backup directory if one is specified in the
database reference file). The original data files that were backed up before the
Fileshare Server was started (and the recovery log files created) should be restored to
their correct directories.
The Rollforward Recovery Utility is invoked using the /r (recover) option.
For example
fs /r dbase.ref [options]
dbase.ref is the name of the database reference file the Rollforward Recovery Utility
uses and is the same one that the Fileshare Server used when it was running. The
Rollforward Recovery Utility reads the database reference file to determine the location
and name of the rollforward recovery log file and the names of the data files to recover.
You can erase entries from the database reference file using the Database Reference File
Maintenance Utility (/e option) before invoking the Rollforward Recovery Utility.
This enables you to restore certain data files that have updates recorded in the
rollforward recovery log file.
You must specifiy a database reference file when invoking the Rollforward Recovery
Utility.
You can specify the following options with the Rollforward Recovery Utility:
/dt date-time
Specifies that the Rollforward Recovery Utility restores the updates made to the data
files up to the time specified. The format of date-time is YYMMDDHHMMSS
(year, month, day, hour, minutes, seconds) specified numerically.
When this option is not specified, the Rollforward Recovery Utility applies all of the
updates that are stored in the rollforward recovery log file.
/v
Causes the Rollforward Recovery Utility to display additional information about which
recovery log files it is searching for and in which directories. It should be used if
more information about the searches that the Rollforward Recovery Utility is performing
is required.
Example
fs /r dbase.ref /dt 931231235959
This example also invokes the Rollforward Recovery Utility using the database reference
file called dbase.ref. Only updates made up to 31 December 1993 are recovered.
Updates from a single Fileshare Server execution can be recorded in multiple log files if
you used a FSView or FSMgr supervisor functions to backup the log file.
(See the section Logging for Rollfoward Recovery - Additional Notes.)
The first recovery log file that the Fileshare Server created when it was active is
called the "starter" log file. Any additional recovery log files that were created, due
to the current log file in use being backed up, are called "continuation" log files.
The Rollforward Recovery Utility, when starting a recovery procedure, scans the log file
directory for the starter log file. If none is found, the diretory is scanned for a
backed up starter log file. If a starter log file still cannot be found the same
procedure is repeated with the searches being performed in the log file backup directory
if one is specified in the database reference file. If the Rollforward Recovery Utility
is able to locate the starter log file then the recovery procedure commences; if not an
error is displayed and the recovery does not start.
Once the starter log file has been processed, the Rollforward Recovery Utility searches
for the continuation log file if there is one. If no backup of the recovery log file was
performed when the Fileshare Server was running, there will be no continuation log file
and the recovery process terminates when all of the records in the starter log file have
been processed.
The Rollforward Recovery Utility seaches for the continuation log file in the log file
directory and then in the log file backup directory. The recovery process then continues
using the continuation log file until all of the updates have been recovered and applied
to the data files.