The archiving of filled groups has these advantages:
- A database backup, together with online and archived redo log files, guarantees that you can recover all committed transactions in the event of an operating system or disk failure.
- If you keep an archived log, you can use a backup taken while the database is open and in normal system use.
- You can keep a standby database current with its original database by continuously applying the original archived redo logs to the standby.
You can configure an instance to archive filled redo log files automatically, or you can archive manually. For convenience and efficiency, automatic archiving is usually best. Figure 13-1 illustrates how the archiver process (ARC0 in this illustration) writes filled redo log files to the database archived redo log.
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If all databases in a distributed database operate in ARCHIVELOG mode, you can perform coordinated distributed database recovery. However, if any database in a distributed database is in NOARCHIVELOG mode, recovery of a global distributed database (to make all databases consistent) is limited by the last full backup of any database operating in NOARCHIVELOG mode.
1. Login sqlplus using sys as sysdba
C:\Users\teguh.triharto>sqlplus
SQL*Plus: Release 11.2.0.1.0 Production on Fri Mar 15 14:26:25 2013
Copyright (c) 1982, 2010, Oracle. All rights reserved.
Enter user-name: sys as sysdba
Enter password:
Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
SQL>
2. Check current archivelog mode in database
SQL> select log_mode from v$database;
LOG_MODE
------------
NOARCHIVELOG
SQL> archive log list
Database log mode No Archive Mode
Automatic archival Disabled
Archive destination USE_DB_RECOVERY_FILE_DEST
Oldest online log sequence 5
Current log sequence 7
SQL>
3. Force a checkpoint to help and speed the database shutdown
SQL> alter system checkpoint;
System altered.
SQL>
4. Shutdown the database
SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL>
5. Start the database in mount mode
SQL> startup mount
ORACLE instance started.
Total System Global Area 744910848 bytes
Fixed Size 1374696 bytes
Variable Size 251659800 bytes
Database Buffers 486539264 bytes
Redo Buffers 5337088 bytes
Database mounted.
SQL>
6. Enable archivelog in the database
SQL> alter database archivelog;
Database altered.
SQL>
7. Open the database
SQL> alter database open;
Database altered.
SQL>
8. Check the current archivelog mode in the database
SQL> archive log list
Database log mode Archive Mode
Automatic archival Enabled
Archive destination USE_DB_RECOVERY_FILE_DEST
Oldest online log sequence 5
Next log sequence to archive 7
Current log sequence 7
SQL> select log_mode from v$database;
LOG_MODE
------------
ARCHIVELOG
SQL>
9. Check parameter log_archive_dest
SQL> show parameter log_archive_dest
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
log_archive_dest string
log_archive_dest_1 string
log_archive_dest_10 string
log_archive_dest_11 string
log_archive_dest_12 string
log_archive_dest_13 string
log_archive_dest_14 string
log_archive_dest_15 string
log_archive_dest_16 string
log_archive_dest_17 string
log_archive_dest_18 string
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
log_archive_dest_19 string
log_archive_dest_2 string
log_archive_dest_20 string
log_archive_dest_21 string
log_archive_dest_22 string
log_archive_dest_23 string
log_archive_dest_24 string
log_archive_dest_25 string
log_archive_dest_26 string
log_archive_dest_27 string
log_archive_dest_28 string
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
log_archive_dest_29 string
log_archive_dest_3 string
log_archive_dest_30 string
log_archive_dest_31 string
log_archive_dest_4 string
log_archive_dest_5 string
log_archive_dest_6 string
log_archive_dest_7 string
log_archive_dest_8 string
log_archive_dest_9 string
log_archive_dest_state_1 string enable
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
log_archive_dest_state_10 string enable
log_archive_dest_state_11 string enable
log_archive_dest_state_12 string enable
log_archive_dest_state_13 string enable
log_archive_dest_state_14 string enable
log_archive_dest_state_15 string enable
log_archive_dest_state_16 string enable
log_archive_dest_state_17 string enable
log_archive_dest_state_18 string enable
log_archive_dest_state_19 string enable
log_archive_dest_state_2 string enable
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
log_archive_dest_state_20 string enable
log_archive_dest_state_21 string enable
log_archive_dest_state_22 string enable
log_archive_dest_state_23 string enable
log_archive_dest_state_24 string enable
log_archive_dest_state_25 string enable
log_archive_dest_state_26 string enable
log_archive_dest_state_27 string enable
log_archive_dest_state_28 string enable
log_archive_dest_state_29 string enable
log_archive_dest_state_3 string enable
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
log_archive_dest_state_30 string enable
log_archive_dest_state_31 string enable
log_archive_dest_state_4 string enable
log_archive_dest_state_5 string enable
log_archive_dest_state_6 string enable
log_archive_dest_state_7 string enable
log_archive_dest_state_8 string enable
log_archive_dest_state_9 string enable
SQL>
10. Check parameter db_recovery_file_dest on C:\app\teguh.triharto\flash_recovery_area\tgh\ONLINELOG
SQL> show parameter db_recovery_file_dest
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
db_recovery_file_dest string C:\app\teguh.triharto\flash_recovery_area
db_recovery_file_dest_size big integer 3852M
SQL>
C:\app\teguh.triharto\flash_recovery_area\tgh\ONLINELOG
11. force generation of some archivelogs
SQL> alter system switch logfile;
System altered.
SQL>