Informix® uses
logical log files for data recovery and consistency. Logical log files
store changes to the Rational® Synergy
database and are stored in the log dbspace. Each Informix server created by Rational Synergy tools contains
a log dbspace. Depending on the configuration of the Informix server, the size of the dbspace
and the number of logical log files stored in it might vary.
In an operational Informix server,
logical log files receive logical log records that are generated from
the following events:
- Structured Query Language (SQL) Data Definition Language (DDL)
statements
- SQL Data Manipulation Language (DML) statements
- Changes to the Informix server
configuration
- Checkpoint
If the Informix server
must roll back a transaction, it uses the corresponding logical log
record to revert the changes initiated by the transaction.
During the data restore operation, you can use logical log files
to do the following tasks:
Before performing a logical log backup, you must thoroughly understand
what the commands do and do not do.
Note: Devise a comprehensive backup plan. Include a regular database
archive/restore and the logical log backup/restore procedure. Test
this backup plan before using it on the production Informix server, and constantly update and
maintain the backup procedures.
Have a high availability solution
for the file system portion of your databases. Informix and the file system must be in
sync at all times.