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

326 Chapter7
Logging and Recovery
Logging Preparation
NOTE Do not give the logid and the log file the same name, because the logid is used
to name the RESTART file (used for DBRECOV STOP/RESTART recovery
explained later in this chapter).
logfile is an MPE/iX file reference that identifies the actual file to which the log
records are written. If the AUTO option is specified, the last three digits
are numeric (001-999). The first log file specified with the MPE/iX GETLOG
command must end with the last three digits equal to 001 if the AUTO
option is used. (A warning message is issued if the log file does not end in
001.) When the AUTO option is used, the next log file will be opened
automatically when the current one is full. The new log file is numbered
consecutively. When the AUTO option is not used, the next log file needs to
be built manually using the CHANGELOG command, when the current log
file is almost full.
DISC is the class of the device on which the log file is to reside. For roll-back
recovery, the log file and the database must be in the same volume set. If
the log file specified for the logid is a serial file, the AUTO/NOAUTO
option is ignored.
TAPE is the class of the device on which the log file is to reside.
password is the password to be associated with the logging identifier. This
parameter protects the log file from unauthorized access. Up to eight
characters are allowed.
AUTO performs an automatic CHANGELOG command when the disk log file
becomes full. A new log file is automatically created with the same log file
name incremented by one in the digit portion; for example, if the current
log file is ORDER001, the next file will be ORDER002. This enables
logging to continue uninterrupted, also creating a sequence of log files or a
log file set.
If you use TurboSTORE/iX 7x24 True-Online Backup (with
ONLINE=START or ONLINE=END) to back up your database and plan
on using DBRECOV for roll-forward recovery, you must properly synchronize
the log files with the backup copy because the log files are automatically
created in a round-robin fashion. The SHOW
database ALL command of
DBUTIL for the restored backup copy gives you the name of the logfile to
begin roll-forward recovery.
NOAUTO is the default. No CHANGELOG command is performed when the disk log file
becomes full.
Example
In the following example, the logid is created with the default NOAUTO option and then
changed to specify the AUTO option. The log file name follows the naming convention
required by the CHANGELOG command. The LISTLOG command is used to check if the logid
exists. The ALTLOG command is used to change the AUTO/NOAUTO option.