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

350 Chapter7
Logging and Recovery
Roll-Forward Recovery
4. Start the log process:
:LOG logid ,START
5. Back up the database using TurboSTORE/iX 7x24 True-Online Backup (with
ONLINE=START or ONLINE=END option) and logfile LOGF001. Let this be backup
number 1.
6. Access the database for modifications. The current log file is LOGF005.
7. Back up the database, while open for access, using TurboSTORE/iX 7x24 True-Online
Backup (with ONLINE=START or ONLINE=END option). Let this be backup
number 2.
Note that LOGF005 was in use. At this point, you have an option to store log files
LOGF001 to LOGF004 to another storage media for added protection. You can then
purge them from the system if you want to continue the log process beyond logfile
LOGF999.
8. Continue accessing the database until there is an interruption (for example, a system
failure). The current log file is LOG009.
9. Reboot the system using the START RECOVERY option.
10.Optionally store the damaged database. Purge database using DBUTIL.
11.Restore the database from backup number 2.
12.Use DBUTIL to disable access and enable recovery. You may use SHOW
database ALL
to get backup information.
13.Use DBRECOV for roll-forward recovery. The root file contains information about the
starting point for recovery. The recovery will start with the logfile LOGF005, following
the backup (DBQUIESCE log records).
14.You can back up the recovered database using TurboSTORE/iX 7x24 True-Online
Backup (with ONLINE=START or ONLINE=END option) to keep recovery time short.
Remember the access flag is disabled and recovery is enabled. When you restore from
this backup for roll-forward recovery, you will not need to execute step 12 above.
15.At this point, you can either restart the logging process (continue with LOGF009) or
start a new log process with LOGF001. If you want to start a new log process, you will
need to stop the log process and remove (optionally store and purge) the log files used so
far, LOGF005 through LOGF009 (or LOGF001 through LOGF009, if you did not purge
in step 7).
Note that if you plan on using TurboSTORE/iX 7x24 True-Online Backup (with
ONLINE=START or ONLINE=END option) for an existing database and logging is
already enabled, you will not need to execute steps 1 through 4.
Recovery from a Stream File
A stream file may specify all of the databases logging to one log file for roll-forward
recovery. If one of the databases has not been restored at the time the stream file is run,
recovery for that database is prevented because recovery for that database is disabled if