Archive log Basic

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What is archive log: 

Copy redo log files to a designated storage device after a log switch has occurred

ARCHIVE processes are present only when the database is in ARCHIVELOG mode and automatic archiving is enabled.

An archived redo log file is a copy of one of the filled members of a redo log group.

It includes the redo entries and the unique log sequence number of the identical member of the redo log group.  

Database Running in noarchivelog Mode:

When you run your database in NOARCHIVELOG mode, you disable the archiving of the redo log

The database control file indicates that filled groups are not required to be archived

NOARCHIVELOG mode protects a database from instance failure but not from media failure

Only the most recent changes made to the database, which are stored in the online redo log groups, are available for instance recovery.

In NOARCHIVELOG mode you cannot perform online  backups


Database Running in archivelog Mode:

When you run a database in ARCHIVELOG mode, you enable the archiving of the redo log

The database control file indicates that a group of filled redo log files cannot be reused by LGWR until the group is archived

A filled group becomes available for archiving immediately after a redo log switch occurs

 

Archive Destination Status:

Valid/Invalid: 

indicates whether the disk location or service name information is specified and valid. 

Enabled/Disabled:  

indicates the availability state of the location and whether the database can use the destination.

Active/Inactive:

indicates whether there was a problem accessing the destination.

 

Archive log Dynamic Views 

V$Archived_log:- 

Display the archive log information from the control file

V$Archive_dest:-

Describe the archive log destination 

V$Log_history:-

Contain log file information from the control file

V$Archive_process:-

Information from the state of the various ARCH process of the instance

Select * from  V$Archive_process

How to check archivelog status:-

SQL> select name,open_mode,log_mode from v$database;

NAME      OPEN_MODE            LOG_MODE

--------- -------------------- ------------

DEV       READ WRITE           NOARCHIVELOG


NAME      OPEN_MODE            LOG_MODE

--------- -------------------- ------------

VIS       READ WRITE           ARCHIVELOG 

 

OS Level:

$ ps  -ef  | grep  -i _arc


How to enable archive log:- 

shutdown

startup mount

SQL> alter database archivelog;

SQL> alter database open;


How to disable archive log:- 

shutdown

startup mount

SQL> alter database noarchivelog;

SQL> alter database open;

How to find archive log location:-

SQL> archive log list

Database log mode              Archive Mode

Automatic archival             Enabled

Archive destination            /u01/oracle/VIS/data

Oldest online log sequence     942

Next log sequence to archive   944

Current log sequence           944

 

How to delete archivelog 

Go rman utility

rman target /

RMAN>List archivelog all;

 archive log details and locations

RMAN>Delete archivelog all;

 Deleted all archive logs

RMAN>List archivelog all;

RMAN>crosscheck archivelog all;

 

Rman target /

 

delete NOPROMPT archivelog all completed before 'sysdate - 1/24';

Exit


Manually clearing the space

Delete the   archive log manually from mount point or  reco  location

Rman taregt  / 

CROSSCHECK ARCHIVELOG ALL;

delete noprompt expired archivelog all;

Exit.

 

How To Change Archive Log Destination? 

Temporarily Changing the Destination Using SQL*Plus

sqlplus / as sysdba

SQL> archive log list;

Database log mode Archive Mode

Automatic archival Enabled

Archive destination /u01/app/oracle/product/10.2.0/db_1/dbs/arch

Oldest online log sequence 9285

Next log sequence to archive 9287

Current log sequence 9287

 To change the location

 

SQL>ARCHIVE LOG START '/u01/arch';

Once verify your changes:

SQL> archive log list;

Database log mode Archive Mode

Automatic archival Enabled

Archive destination /u01/arch

Oldest online log sequence 9285

Next log sequence to archive 9287

Current log sequence 9287

 

Permanently Changing the Destination Using SQL*Plus

sqlplus / as sysdba

ALTER SYSTEM SET log_archive_dest ='/u01/arch' scope=both;

To Verify your changes:

 

SQL> archive log list;

Database log mode Archive Mode

Automatic archival Enabled

Archive destination /u01/arch

Oldest online log sequence 9285

Next log sequence to archive 9287

Current log sequence 9287   

  

Known Issues:

ORA-38774: cannot disable media recovery - flashback database is enabled


SQL> alter database noarchivelog;

alter database noarchivelog

*

ERROR at line 1:

ORA-38774: cannot disable media recovery - flashback database is enabled

SQL> show parameter flash

NAME                                 TYPE        VALUE

------------------------------------ ----------- ------------------------------

db_flash_cache_file                  string

db_flash_cache_size                  big integer 0

db_flashback_retention_target        integer     1440

 

SQL> show parameter reco

NAME                                 TYPE        VALUE

------------------------------------ ----------- ------------------------------

control_file_record_keep_time        integer     50

db_recovery_file_dest                string      +RECO

db_recovery_file_dest_size           big integer 49888G

db_unrecoverable_scn_tracking        boolean     TRUE

recovery_parallelism                 integer     0

remote_recovery_file_dest            string

SQL>

 

SQL> select name,flashback_on from v$database;

NAME      FLASHBACK_ON

--------- ------------------

TEST    YES

 

SQL> alter database flashback off;

Database altered.

 

SQL> select name,flashback_on from v$database;

NAME      FLASHBACK_ON

--------- ------------------

TEST    NO

 

SQL> alter database noarchivelog;

Database altered.

SQL> alter database open;

Database altered.

 

SQL> archive log list

Database log mode              No Archive Mode

Automatic archival             Disabled

Archive destination            USE_DB_RECOVERY_FILE_DEST

Oldest online log sequence     84

Current log sequence           87

SQL>

 

 

Error:

RMAN> Delete archivelog until time 'sysdate-1/24';

 

allocated channel: ORA_DISK_1

channel ORA_DISK_1: SID=5914 device type=DISK

RMAN-08137: warning: archived log not deleted, needed for standby or upstream capture process

archived log file name=+DATA/CEBS7D/ARCHIVELOG/2021_12_29/thread_1_seq_200.2595.1092604797 thread=1 sequence=200

RMAN-08137: warning: archived log not deleted, needed for standby or upstream capture process

 

Solution:

RMAN utility and execute below command and retest the issue

CROSSCHECK ARCHIVELOG ALL;

DELETE EXPIRED ARCHIVELOG ALL;

delete force NOPROMPT archivelog all completed before 'sysdate - 1';

 

 

Refer: 

How to Enable/Disable Archive Log Mode In 10g and 11g (Doc ID 371139.1)


How To Change Log Archive Destination While the Database Is Open When the Archive Destination Is Full (Doc ID 160446.1)

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