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Oracle 11g archiving mode

To understand the archiving mode of oracle, you need to understand how oracle works. To put it simply, oracle records all data processing tasks (transactions), and everything is recorded in a log.

To put it simply, to turn on the archive mode is to set up oracle to archive the logs of the operation database into files and save them to the specified location.

The default non-archive mode is to discard these logs.

After oracle is installed, archive mode is not enabled by default.

What is the use of archiving logs?

Archive log is the full record of data transactions processed by oracle, that is, all the operation sequence and contents of data operations by oracle.

With the archive log, you can know exactly when and what oracle did.

Oracle can restore the database to any point in time according to the archived log, as long as the archived log must be complete and there is no break in the middle.

This plays a very important role in the failure recovery of oracle database.

1. Check to see if the database is in archive mode

[oracle@testdb ~] $sqlplus / as sysdba

SQL*Plus: Release 11.2.0.3.0 Production on Mon Nov 10 21:42:13 2014

Copyright (c) 1982, 2011, Oracle. All rights reserved.

Connected to:

Oracle Database 11g Enterprise Edition Release 11.2.0.3.0-64bit Production

With the Partitioning option

SQL > archive log list

Database log mode No Archive Mode

Automatic archival Disabled

Archive destination USE_DB_RECOVERY_FILE_DEST

Oldest online log sequence 1

Current log sequence 3

SQL >

SQL > archive log list

two。 Modify the database to archive mode.

Must be modified in mount state.

SQL > shutdown immediate

Database closed.

Database dismounted.

ORACLE instance shut down.

SQL > startup mount

ORACLE instance started.

Total System Global Area 784998400 bytes

Fixed Size 2232472 bytes

Variable Size 473960296 bytes

Database Buffers 306184192 bytes

Redo Buffers 2621440 bytes

Database mounted.

SQL > alter database archivelog

Database altered.

SQL > alter database open

Database altered.

3. View where the archive log is saved

SQL > archive log list

Database log mode Archive Mode

Automatic archival Enabled

Archive destination USE_DB_RECOVERY_FILE_DEST

Oldest online log sequence 1

Next log sequence to archive 3

Current log sequence 3

SQL >

4. Modify the location of the archive log

Starting with oracle10g, archived logs can be saved in two locations at the same time in case of accidents.

SQL > alter system set log_archive_dest_1='location=/data/oracle/log1/archive_log'

SQL > alter system set log_archive_dest_2='location=/data/oracle/log2/archive_log'

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