Format for LOG_ARCHIVE_FORMAT in Oracle

LOG_ARCHIVE_FORMAT parameter controls the format of the archive log file name. This parameter can only be used when the redo log is in ARCHIVELOG mode . LOG_ARCHIVE_FORMAT parameter is static in nature so it comes into action after restart of the instance. If the format defined in the parameter log_archive_format is invalid the database will startup but archiver will fail to archive logs which will cause database to hang and in the alert log the following message would be reported .

 “ORA-00294: invalid archivelog format specifier..” 

So if we change this parameter a quick test can be done by running the above SQL to make sure oracle is able to archive the redo log.

The format of specifying the archive redo log filename is given below :

LOG_ARCHIVE_FORMAT = “LOG%s_%t_%r.arc”
Various parameters that can be used with the LOG_ARCHIVE_FORMAT parameter are given below:
%s – log sequence number
%S – log sequence number, padded with zero
%t – thread number
%T – thread number, padded with zero
%a – activation id
%d – database id
%r – reset logs id

Whenever uppercase is used for a variable, such as %S or %T, it forces the value of the variable to be of fixed length, and the value to the left is padded with zeros.

Below is the Demo of the log_archive_format parameters.

SQL> alter system set log_archive_dest_1='location=D:\archive\';
System altered.

SQL> archive log list
Database log mode              Archive Mode
Automatic archival             Enabled
Archive destination            D:\archive\
Oldest online log sequence     11
Next log sequence to archive   13
Current log sequence           13
        
SQL> alter system set log_archive_format='noida_%s_%t_%r.arc' scope=spfile;
System altered.

SQL> shut immediate
SQL>startup

SQL> archive log list
Database log mode              Archive Mode
Automatic archival             Enabled
Archive destination            D:\archive\
Oldest online log sequence     11
Next log sequence to archive   13
Current log sequence           13

SQL> alter system switch logfile;
System altered.

Now the  new archive log file  name  like  'NOIDA_13_1_749730106.ARC'

For more click here 


Enjoy       :-)

Difference Between LOG_ARCHIVE_DEST and LOG_ARCHIVE_DEST_1

Once  my friend call me and told that he has confusion about the  LOG_ARCHIVE_DEST and LOG_ARCHIVE_DEST_n . I explain him and decided to post it here .

LOG_ARCHIVE_DEST is applicable only if we are running the database in ARCHIVELOG mode. LOG_ARCHIVE_DEST parameter are used to specified the archiving location. The Location specified by log_archive_dest must be local . We choose to archive only two local location  i.e,  primary and a secondary destination ( using LOG_ARCHIVE_DEST and LOG_ARCHIVE_DUPLEX_DEST ) .

The  LOG_ARCHIVE_DEST_n initialization parameter defines up to ten (where n = 1, 2, ... 10) destinations in oracle 10g and thirty one (n=1,2....31)  destination in oracle 11g , each of which must specify either the  LOCATION or  the SERVICE  attribute to specify where to archive the redo data. All other attributes are optional.We set the attributes for the LOG_ARCHIVE_DEST_n initialization parameter to control different aspects of how redo transport services transfer redo data from a production or primary database destination to another (standby) database destination.For every LOG_ARCHIVE_DEST_n initialization parameter that we define, we must specify a corresponding LOG_ARCHIVE_DEST_STATE_n parameter. The LOG_ARCHIVE_DEST_STATE_n (where n is an integer from 1 to 10) initialization parameter specifies whether the corresponding destination is currently enabled or disabled.

LOG_ARCHIVE_DEST is incompatible with the LOG_ARCHIVE_DEST_n parameters, and must be defined as the null string ("") or (' ') when any LOG_ARCHIVE_DEST_n parameter has a value other than a null string.

If we are using Oracle Enterprise Edition, LOG_ARCHIVE_DEST parameter is deprecated in favor of the LOG_ARCHIVE_DEST_n parameters. If Oracle Enterprise Edition is not installed or it is installed but we have not specified any LOG_ARCHIVE_DEST_n parameters,then LOG_ARCHIVE_DEST parameter is valid. If we have LOG_ARCHIVE_DEST parameter set and we have to set more than two archive location then follow the below steps :

SQL> alter system reset log_archive_dest='' scope=both;

SQL> shutdown immediate

SQL> startup

SQL> alter system set log_archive_dest_1='location=C:\archive\' ;

SQL> alter system set log_archive_dest_2='location=D:\oracle\archive\' ;

Enjoy      : -)

Control File Contents

A control file contains information about the associated database that is required for access by an instance, both at startup and during normal operation. Control file information can be modified only by Oracle Database; no database administrator or user can edit a control file. It contains (but is not limited to) the following types of information :

• Database information (RESETLOGS SCN and their time stamp)
• Archive log history
• Tablespace and datafile records (filenames, datafile checkpoints, read/write status, offline or not).
• Redo threads (current online redo log)
• Database's creation date
• database name
• current archive log mode
• Log records (sequence numbers, SCN range in each log)
• RMAN catalog
• Database block corruption information
• Database ID, which is unique to each DB.                                                                                                                                                                                                                                                                                              

The location of the control files is specified through the control_files init parameter file .


Size of control files :
The size of the control files is governed by the following parameters

• maxlogfiles
• maxlogmembers
• maxloghistory
• maxinstances
• control_file_record_keep_time

Sections :

The controlfile contains the following sections:

Archives Log (reusable)

Backup Corruption (reusable)

Backup Datafile (reusable)

Backup Piece (reusable)

Backup Redolog (reusable)

Backuo Set (reusable)

Backup spfile

CKPT Process

Copy Corruption (reusable)

Datafile

Datafile Copy (reusable)

Datafile History

Database Incarnation

Deleted Objects (reusable)

Filename

Flashback Log

Instance Space Reservation

Log History (reusable)

MTTR

Offline Range (reusable)

Recovery Destination

Removable Recovery Files

Rman Status

Rman Configuration

Redo Threads

Redo Logs

Tablespace

Temporary Filename

Thread Instance Name Mapping

Proxy Copy

The  minimum  number of  days that  a  reusable  record  is kept  in  the  controlfile is controlled  by  the control_file_record_keep_time parameter. These sections consist of records. The size, total number  and number of used record are exposed through v$controlfile_record_section.

To Check the information inside controlfile  use the below command  :
SQL> alter database backup controlfile to trace as   'C:\CREATE_CONTROL.sql' ;




Enjoy      :-)