Lesson 1

In the previous modules, we explored the different enhancements in Recovery Manager (RMAN) and backup strategies. In this module, we will look at the following components in backup and recovery:

1. Improvements in export and import
2. Duplex or multiple archive logs
3. Detect and repair of corrupted blocks
4. LogMiner
5. Reports and lists about backups
6. V$ data dictionary views for backup and recovery

When you have completed this module, you will be able to:

1. Define multiple locations for archive log files
   
2. Use DBMS_REPAIR package to detect and repair corrupt blocks
3. Use LogMiner to query the archive log files
4. Use the LIST and REPORT commands within RMAN
5. Query the data dictionary for backup views
6. Describe the improvements in export and import

Starting with Oracle Database 10g, automatic archiving for an Oracle database is enabled with the following SQL command:

ALTER DATABASE ARCHIVELOG

If the database is in ARCHIVELOG mode, Oracle marks the redo logs for archiving as it fills them. The full log files must be archived before they can be reused. The ALTER DATABASE ARCHIVELOG command will by default turn on automatic archiving and the archivers are started. Prior to Oracle Database 10g, log files marked as ready for archiving did not mean they would be automatically archived. You also needed to set a parameter in the initialization file with the syntax:

LOG_ARCHIVE_START = TRUE

Setting this parameter started an Oracle process to copy a full redo log to the archive log destination. The archive log destination and the format for the archived redo log names are specified using two additional parameters, LOG_ARCHIVE_DEST and LOG_ARCHIVE_FORMAT. A setting such as the following:

LOG_ARCHIVE_DEST = C:\ORANT\DATABASE\ARCHIVE

specifies the directory to which Oracle writes the archived redo log files, and:

LOG_ARCHIVE_FORMAT = ORCL%t_%s_%r.arc

defines the format Oracle will use for the archived redo log filenames. In this case, the filenames will begin with ORCL and will end with .arc. The parameters for the format wildcards are:

%t
Include thread number as part of the filename
%s
Include log sequence number as part of the filename
%r
Include resetlogs ID as part of the filename