TurboIMAGE/XL Database Management System Reference Manual MPE/iX V6.5 (30391-90011)

328 Chapter7
Logging and Recovery
Logging Preparation
:RUN DBUTIL.PUB.SYS
>>SET ORDERS LOGID = ORDERLOG
PASSWORD:? PASSLOG If no logid password was previously specified
in the GETLOG command, you would press Return
at the prompt.
DBUTIL checks the validity of the logid with MPE/iX, and reports a warning as follows if
the log identifier is not valid or if its password is incorrect:
WARNING: non-existent LOGID
Once the log identifier has been set into the database, the log identifier parameters cannot
be altered for the logging and recovery system to function correctly.
Step 7--Setting Flags for the Database Backup Copy
In addition to setting the log identifier, certain flags need to be set for the database before
creating the backup. Some flags such as LOGGING, ROLLBACK, and MUSTRECOVER need to be
set only once and can remain enabled unless you change your recovery plan. However, the
database access flag is disabled before the backup and enabled (access allowed) after the
backup. On the contrary, the recovery flag is enabled before the backup and disabled after
the database is recovered. This is done before someone starts accessing the database to
facilitate the recovery of the database after it is restored from the backup copy. If you plan
on using TurboSTORE/iX 7x24 True-Online Backup (with ONLINE=START or
ONLINE=END) option to back up the database, when it is open for access, you will not be
able to disable the database access flag and enable the recovery flag. If recovery becomes
necessary, you can set these two flags immediately after restoring from the backup and
before starting the recovery process. Use DBUTIL to set the following flags in the root file
before making the backup copy of the database:
• Enable Logging Flag. This flag ensures that all database modifications are logged
and available for later use by the recovery system, if necessary. When you enable the
database for logging, DBUTIL checks whether a database backup copy has been stored
with DBSTORE or TurboSTORE/iX 7x24 True-Online Backup (with ONLINE=START or
ONLINE=END). If not, DBUTIL issues a warning message. Because the database is
stored after logging has been first enabled, the DBUTIL warning message can be
interpreted as a prompt to store the database. If you plan to use roll-forward recovery,
use the following command to enable logging (implies roll-forward logging):
>>ENABLE database name FOR LOGGING
WARNING: database modified and not DBSTOREd
If you plan to use roll-back recovery, enabling the roll-back flag will automatically
enable the logging flag.
Remember that, if logging to disk, the log identifier must be created before the
preceding command can execute successfully (refer to "Step 5--Creating the Log
Identifier").