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

348 Chapter7
Logging and Recovery
Roll-Forward Recovery
Performing Roll-Forward Recovery
To complete the transaction roll-forward process following a hard system failure, perform
the following steps:
1. Following a start recovery operation to bring up the system, locate the applicable log
file medium to be used for roll-forward recovery.
If logging to tape, the correct tape needs to be mounted. If using the MPE/iX CHANGELOG
feature and there are multiple log file tapes, this will be the first tape in the series if
DBSTORE was used. If TurboSTORE/iX 7x24 True-Online Backup (with
ONLINE=START or ONLINE=END option) was used to backup the database and
AUTO option is used, this may not be the first file in the series. If logging to disk,
TurboIMAGE/XL automatically locates the first log file in the given logging cycle after
checking for the logid in the root file. When TurboSTORE/iX 7x24 True-Online Backup
(with ONLINE=START or ONLINE=END option) is used, necessary information such
as the log file name in use, log file record numbers, date, and time of backup is recorded
in the root file before backup. When the database is restored from this backup, the SHOW
database ALL command of DBUTIL displays this information.
Note that the system boot-up process writes a crash record to the last volume of the
user log set. If a start recovery operation is not performed, this will not occur, causing
DBRECOV to issue a warning.
2. Check your backup listings to see when your database was last stored. If time permits,
store your damaged database with DBSTORE. Having a current backup of your damaged
database is an extra measure to protect against lost data due to a damaged log file.
3. Restore the backup of the database; this backup was created at the beginning of the
current logging maintenance cycle. Use the SHOW
database command of DBUTIL to
find out which log file will be used to start recovery. If the TurboSTORE/iX 7x24
True-Online Backup (with ONLINE=START or ONLINE=END option) was used for
backup, the log file name is displayed. Otherwise, it will be the first log file in this
logging cycle.
4. Enter the following MPE/iX command:
:RUN DBRECOV.PUB.SYS
5. If you used the MPE/iX STORE command without ONLINE=START or ONLINE=END
option to store the database when you started your logging cycle, enter the >CONTROL
NOSTORE command of DBRECOV.
6. Enter the DBRECOV >RECOVER command below (where database name is the name of
the individual database to be recovered):
>RECOVER database name [, database name2 ,..., database nameN ]
7. Enter all other desired DBRECOV commands (>FILE, >CONTROL with other options
except NOSTORE shown above, and >PRINT.) Refer to chapter 8 for more information.
8. If you want to recover the database(s), enter the DBRECOV >RUN command. Otherwise,