Log Files in Oracle DBA
Redo log files (minimum 4m in ORACLE 10g
Reasons for maintaining redolog files;
1 Fast commit mechanism
2 Roll farward mechaninm & rollbackward mechanism [through smon]
3 Recovery operations [through archive files]
To enable orachive mod
In init. Ora file
Up to ORACLE 9i log_archive_start = time
Log_archive_dest= /disk3/oradata/pol/arch
Log_archive_format= %s.arc
In ORACLE 10 g log-archive-dest= % t_%s_%r.arc
%t thread no. [instance]
%s sequence no.
%r resetlog id
NOTE the database should be in mount stage to enable archive log files.
Demo: Redolog file management
SYS> select member from vi$logfile;
SYS> select member, group# form v$logfile;
SYS> desc v$log
SYS> select group#, members, status form v$log;
SYS> save vdlog
SYS> alter system switchlogfile;
[for manual swithch]
SYS> alter database add logfile group3;
‘disk3/oradata/pal/redo3.dbf’size 4m;
SYS> @vdlog
Group1
Group2
Group 3 unused
SYS> alter system switch logfile;
SYS> alter system switch logfile;
SYS> @vdlog
To drop the redo log file, it’s status should be ‘INACTIVE’
SYS> alter database drop logfile group3;
Enabling the database into archive log mode
Dba 12 ~] $ sq!plus ‘/as sysdba’
SYS> startup
SYS> archive log list
Archive log disable
SYS> shut immediate
SYS> !
Dba12 ~]$ cd $ORACLE_HOME/ dbs
Dba12 dbs] $ vi initrajpar.ora
Log_archive_dest=disk3/oradatga/pal/arch
:wq
Dba12 dbs ] $ cd /disk3/oradata/pal/
Dba12 pal]$ mkdir arch
Dba12 pal] $ ls
Dba12 pal]$ exit
SYS > startup mount
SYS> alter database archivelog;
SYS> alter database open;
SYS> archive log list
Archivelog enable
SYS> !ps - x
SYS> grant connect, resource to user 2
Identified by user2;
SYS> conn user 2 / user 2
User2> ! demobld user 2 / user2
User 2> select * from tab;
User 2> insert inot emp select * from emp;
User 2 > /
User 2 > / [up to some thousands of records]
User2> !
Dba12 ~] $ cd / disk 3 /oradata /pal /arch
Dba12 arch ] $ ls
