RESIZING ONLINE REDOLOG FILES

The following demonstration shows how to resize the online redo log files in an oracle database.

The query below gives the size of all the online redo log files which is 250MB.

SQL> SELECT a.group#, a.member, b.bytes FROM v$logfile a, v$log b WHERE a.group# = b.group#;

    GROUP# MEMBER                                                  BYTES

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

         1 /fs02/oradata/demo/demo_redo1a.log            262144000

         1 /fs03/oradata/demo/demo_redo1b.log            262144000

         1 /fs04/oradata/demo/demo_redo1c.log            262144000

         2 /fs02/oradata/demo/demo_redo2a.log            262144000

         2 /fs03/oradata/demo/demo_redo2b.log            262144000

         2 /fs04/oradata/demo/demo_redo2c.log            262144000

         3 /fs02/oradata/demo/demo_redo3a.log            262144000

         3 /fs03/oradata/demo/demo_redo3b.log            262144000

         3 /fs04/oradata/demo/demo_redo3c.log            262144000

9 rows selected.

Check the status of the log group.

SQL> select group#, status from v$log;

    GROUP# STATUS

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

         1 CURRENT

         2 INACTIVE

         3 INACTIVE

Now force a log switch until the last redo log is marked "CURRENT" by issuing the following command:

SQL> alter system switch logfile;

SQL> alter system switch logfile;

SQL> select group#, status from v$log;

    GROUP# STATUS

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

         1 INACTIVE

         2 INACTIVE

         3 CURRENT

Drop the first logfile group and recreate the same with the desired size, in this case 512MB

SQL> alter database drop logfile group 1;

Database altered.

or

SQL> alter database drop logfile group 1;

ALTER DATABASE DROP LOGFILE GROUP 1

*

ERROR at line 1:

ORA-01624: log 1 needed for crash recovery of instance ORA920 (thread 1)

ORA-00312: online log 1 thread 1: '<file_name>'

Nothing to panic here and this is an easy problem to resolve. Simply perform a checkpoint on the database and try to drop again.

SQL> alter system checkpoint global;

System altered.

SQL> alter database drop logfile group 1;

Database altered.

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

Re-create the dropped redo log group with different size

alter database add logfile group 1 (

   '/fs02/oradata/demo/demo_redo1a.log', 

   '/fs03/oradata/demo/demo_redo1b.log',

   '/fs04/oradata/demo/demo_redo1c.log') size 500m reuse;

After re-creating the online redo log group, force a log switch. The online redo log group just created should become the "CURRENT" one.

SQL> select group#, status from v$log;

    GROUP# STATUS

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

         1 UNUSED

         2 INACTIVE

         3 CURRENT

SQL> alter system switch logfile;

SQL> select group#, status from v$log;

    GROUP# STATUS

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

         1 CURRENT

         2 INACTIVE

         3 ACTIVE

Do the same for all the logfiles.

alter database add logfile group 2 (

   '/fs02/oradata/demo/demo_redo2a.log', 

   '/fs03/oradata/demo/demo_redo2b.log',

   '/fs04/oradata/demo/demo_redo2c.log') size 500m reuse;

alter database add logfile group 3 (

   '/fs02/oradata/demo/demo_redo3a.log', 

   '/fs03/oradata/demo/demo_redo3b.log',

   '/fs04/oradata/demo/demo_redo3c.log') size 500m reuse;

Now, if you check the sizes of the logfiles you can see the size increased.

SQL> SELECT a.group#, a.member, b.bytes FROM v$logfile a, v$log b WHERE a.group# = b.group#;

    GROUP# MEMBER                                                  BYTES

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

         1 /fs02/oradata/demo/demo_redo1a.log            524288000

         1 /fs03/oradata/demo/demo_redo1b.log            524288000

         1 /fs04/oradata/demo/demo_redo1c.log            524288000

         2 /fs02/oradata/demo/demo_redo2a.log            524288000

         2 /fs03/oradata/demo/demo_redo2b.log            524288000

         2 /fs04/oradata/demo/demo_redo2c.log            524288000

         3 /fs02/oradata/demo/demo_redo3a.log            524288000

         3 /fs03/oradata/demo/demo_redo3b.log            524288000

         3 /fs04/oradata/demo/demo_redo3c.log            524288000

9 rows selected.

Mission accomplished. :-)

Re-Linking Of Oracle Binaries

Today one of our servers crashed and the server (whole server) was restored from the backup. It took some time to be restored one by one. Meanwhile when things are set, I tried to startup the database, I got a different error that I have not seen that before.

/home/oracle /> sqlplus "/ as sysdba"

/usr/lib/pa20_64/dld.sl: Unsatisfied code symbol 'gethrtime' in load module '/mnt1/app/oracle/product/9.2.0/bin/sqlplus'.

Abort(coredump)

This surely is not due to a database fault. When searched for solutions, found that this is the problem with relinking of oracle binaries.

Relinking of oracle binaries takes place automatically when -

            - An Oracle product has been installed with an Oracle provided installer.

            - An Oracle patch set has been applied via an Oracle provided installer.

Let's look how to relink oracle binaries, if it requires at times. At times! Those times are when -

            - An OS upgrade has occurred.

            - A change has been made to the OS system libraries. This can occur during the application of an OS patch.

            - A new install failed during the relinking phase.

            - Individual Oracle executables core dump during initial startup.

            - An individual Oracle patch has been applied with explicit relink instructions or the relink is integrated into the patch install script.

Step 1 : Login as Oracle user and Set environment parameters such as $ORACLE_HOME, $ORACLE_BASE, $PATH, $LD_LIBRARY_PATH

Step 2 : Shut down all databases and listeners running on the server.

Step 3 : Relink the components as given below for different version of oracle

Oracle Version 7.3.x

For executables: oracle, exp, imp, sqlldr, tkprof

cd $ORACLE_HOME/rdbms/lib

make -f ins_rdbms.mk install

For executables: svrmgrl, svrmgrm

cd $ORACLE_HOME/svrmgr/lib

make -f ins_svrmgr.mk linstall minstall

linstall is for svrmgrl, minstall is for svrmgrm

For executables: sqlplus

cd $ORACLE_HOME/sqlplus/lib

make -f ins_sqlplus.mk install

For executables: dbsnmp, oemevent, oratclsh

cd $ORACLE_HOME/network/lib

make -f ins_agent.mk install

For executables: names, namesctl

cd $ORACLE_HOME/network/lib

make -f ins_names.mk install

For executables: tnslsnr, lsnrctl, tnsping, csmnl, trceval, trcroute

cd $ORACLE_HOME/network/lib

make -f ins_network.mk install

Oracle Version 8.0.x

For executables: oracle, exp, imp, sqlldr, tkprof, mig, dbv, orapwd, rman, svrmgrl, ogms, ogmsctl

cd $ORACLE_HOME/rdbms/lib

make -f ins_rdbms.mk install

For executables: sqlplus

cd $ORACLE_HOME/sqlplus/lib

make -f ins_sqlplus.mk install

For executables: dbsnmp, oemevent, oratclsh, libosm.so

cd $ORACLE_HOME/network/lib

make -f ins_oemagent.mk install

For executables: tnslsnr, lsnrctl, namesctl, names, osslogin, trcasst, trcroute

cd $ORACLE_HOME/network/lib

make -f ins_network.mk install

Oracle version 8.1.x (8i) or higher

A "relink" script is provided in the $ORACLE_HOME/bin directory and can be run as follows.

cd $ORACLE_HOME/bin

relink

$ relink >parameter<

accepted values for parameter: all, oracle, network, client, client_sharedlib, interMedia, precomp, utilities, oemagent

Or else you can even do individually one by one as done for version 8.0.x with a few changes stated below.

Others remain same.

For executables: names, namesctl

cd $ORACLE_HOME/network/lib

make -f ins_names.mk install

For executables: osslogin, trcasst, trcroute, onrsd, tnsping

cd $ORACLE_HOME/network/lib

make -f ins_net_client.mk install

For executables: tnslsnr, lsnrctl

cd $ORACLE_HOME/network/lib

make -f ins_net_server.mk install

Note : There are no "Relink success" messages displayed at the terminal. If the relink was failure, it will terminate with errors such as 'Fatal error', 'Ld: fatal', 'Exit Code 1.

For HP-UX servers, the relink may fail even when done manually. This is a bug and can be rectified by applying the following OS patches as per Oracle support.

For 11.0: HP/UX patches PHCO_23770, PHCO_23092 must be applied.

For 11.11: HP/UX patches PHCO_29029 and PHCO_25569 must be applied.

Retrieve deleted rows from table using audit.

Firstly connect as scott from any other user.

Conn scott/tiger

select * from emp;

SQL> DELETE FROM EMP WHERE EMPNO = 7499;

Now lets retrieve this row by using audits and flashback.

I have mentioned using audits as the row may be accidentally deleted or even deleted by any malicious activity (some unauthorised person performing the delete operation)

If it's due to malicious activity, we can also find the culprit who performed the act.

Check what audit is recorded in the database.

SQL> SELECT NAME, value FROM v$parameter WHERE NAME LIKE 'audit%';

NAME

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

VALUE

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

audit_sys_operations

FALSE

audit_file_dest

D:\ORACLE\PRODUCT\10.2.0\ADMIN\10gDB\ADUMP

audit_trail

DB

The audit is being done to the DB (Mostly DB audit would be done)

Now lets get some details from sys.aud$ table which is the table used for storing audit related things.

SQL> SELECT userid, action#, STATEMENT, OBJ$NAME, To_Char (timestamp#, 'mm/dd/yyyy hh24:mi:ss') FROM sys.aud$ ORDER BY timestamp# asc;

Output would look like this

Timeline from the database audit:

USERID	ACTION#	STATEMENT	OBJ$NAME	TIMESTAMP
SCOTT	101	1		04/30/2006 09:11:36
SCOTT	3	2	X$NLS_PARAMETERS	04/30/2006 09:29:07
SCOTT	3	2	GV$NLS_PARAMETERS	04/30/2006 09:29:07
SCOTT	3	2	V$NLS_PARAMETERS	04/30/2006 09:29:07
SCOTT	3	2	NLS_SESSION_PARAMETERS	04/30/2006 09:29:07
SCOTT	3	5	DUAL	04/30/2006 09:29:07
SCOTT	100	1		04/30/2006 09:29:41
SCOTT	3	22	OBJ$	04/30/2006 09:31:07
SCOTT	3	22	USER_OBJECTS	04/30/2006 09:31:07
SCOTT	3	28	EMP	04/30/2006 09:32:01
SCOTT	3	31	EMP	04/30/2006 09:32:20
SCOTT	7	37	EMP	04/30/2006 09:33:28
SCOTT	3	46	EMP	04/30/2006 09:35:24
SCOTT	7	52	EMP	04/30/2006 09:37:04
SCOTT	7	55	EMP	04/30/2006 09:37:13
SCOTT	3	61	EMP	04/30/2006 09:37:28

Now we have to find which action# refers to what operation. To find this issue the command below.

SQL> SELECT * FROM AUDIT_ACTIONS;

Now you can see action# 7 denotes delete operation.

Delete operation was performed around 9 37. So we want to flashback to before then so have to get the recorded timestamp. Oracle does not actually record a full timeline. Only takes the time every 5 minutes with the relevant SCN.

So now we will find the scn according to the timestamp from the below command which would be stored for maximum 5 days rolling figure.

SQL> SELECT To_Char(TIME_DP, 'dd/mm/yyyy hh24:mi:ss'), SCN_BAS FROM SYS.SMON_SCN_TIME order by scn_bas;

Now you can retrieve the deleted row by flashback the table to before the timestamp where the data is deleted.

SQL> CREATE TABLE EMPCOPY AS SELECT * FROM SCOTT.EMP AS OF TIMESTAMP (TO_TIMESTAMP('30/04/2006 09:31:10','DD-MM-YYYY:HH24:MI:SS'));

where 09:31:10 is the predecessor scn timestamp before the data deletion time of 09:37:13.

Now you can find the deleted row back in the EMPCOPY table.

Let's now find out did SCOTT do this deletion activity or any other malicious user did this on purpose to get SCOTT into trouble.

We can use the same sys.aud$ table to find this too..

SQL> SELECT userid, USERHOST, TERMINAL, SPARE1, action#, STATEMENT, OBJ$NAME, To_Char (timestamp#, 'mm/dd/yyyy hh24:mi:ss') FROM sys.aud$ ORDER BY timestamp# asc;

This additional data shows that SCOTT was coming from a different workstation from normal additionally the SPARE1 column shows that the Windows username was in fact SELVA and not SCOTT.

So take actions accordingly.

Ora - 00600 [13013], [5001]

I experience an Ora-00600 error. Let's look what is the error and the way to resolve it.

Error received

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

ORA-00600: internal error code, arguments: [13013], [5001], [4722], [29361923], [9], [29361923], [17], []

Let's look into details of how to solve this issue.

Section 1> What information needs to be Collected

ORA-600 [13013] [a] [b] [c] [d] [e] [f]

This format relates to Oracle Server 8.0.3 to 10.1

Arg [a] Passcount

Arg [b] Data Object number

Arg [c] Tablespace Relative DBA of block containing the row to be updated

Arg [d] Row Slot number

Arg [e] Relative DBA of block being updated (should be same as [c])

Arg [f] Code

The Second argument would give the information about the data object id.

This would give information about the object involved.

SQL> Select object_name,object_type,owner from dba_objects where data_object_id=<value reported in argment b>;

Once the Object is identified run the following :

The below command check if the table has corruption or not .

SQL> Analzye table <owner>.<table name> validate structure online;

If this goes fine table doesnot have corruption. For next command.

If the above command fails with ORA-1498 go to Section 3

The below command check if table/index has corruption or not

SQL> Analzye table <owner>.<table name> validate structure cascade online;

If the above command errors out with ora-1499 it indicates a corruption in index.

Go to section 2 for resolution

Run dbverify on the datafile reported in the error

Arg [c] in the ora-0600[13011] would give the Relative DBA

For example

ORA-00600: internal error code, arguments: [13013], [5001], [57353], [155254965], [261], [151062605], [17], []

Arg [c] --> rdba-->155254965

Use this value and find the file and block number for this dba(data block address)

SQL> select dbms_utility.data_block_address_file(155254965) Rfile# ,dbms_utility.data_block_address_block(155254965) "Block#" from dual;

RFILE# Block#

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

37 65717

You can run dbveirfy on datafile with rfile#=37

SQL> Select name from v$datafile where rfile#=37;

$ dbv file=<location of datafile> blocksize=<db_block_size>

Section 2 > How to resolve if an Index is corrupted.

You would need to drop and recreate the index
Ensure before dropping the Index

SQL> Spool /tmp/createindex.sql
SQL> Set long 100000000
SQL> Select dbms_metadata.get_ddl('INDEX','<Index name>',<'user name>') from dual;
SQL> Spool off

To Identify the index please do the following

Analyze table with "validate structure cascade" fails with ORA-1499 and the trace file contains message "Table/Index row count mismatch". Example:

SQL> analyze table test validate structure cascade;
analyze table test validate structure cascade
*
ERROR at line 1:
ORA-01499: table/index cross reference failure - see trace file 

The associated trace file contains:

Table/Index row count mismatch
table 6559 : index 10000, 0
Index root = tsn: 6 rdba: 0x01400091

It means: A table scan returned 6559 rows and an index scan returned 10000 rows.
"Index root" is the segment header information for the index:
rdba: 0x01400091 is the Index segment header relative data block address. It is decimal 20971665 which is Rfile#=5 Block#=145 :

SQL> select dbms_utility.data_block_address_file(20971665)  "Rfile#"  
2          ,dbms_utility.data_block_address_block(20971665) "Block#"  
3 from dual;  

Rfile#     Block#  
---------- ----------  
5          145  

Running the next query can identify the associated index:

QUERY 1: 

SQL> select owner, segment_name, segment_type 
2    from  dba_segments 
3    where header_file = 5 
4      and header_block = 145; 

OWNER    SEGMENT_NAME    SEGMENT_TYPE 
-------- --------------- ------------------ 
SCOTT    I_TEST          INDEX 

Section 3> How to resolve if table is corrupted

Option a> Backup is available

Ora-1498 would be reported on the table.

The trace file from Ora-1498 would contain following information

Example

Block Checking: DBA = 1066265208, Block Type = KTB-managed data block --->
file 254,block 911992
data header at 0xc00000010118e07c
kdbchk: avsp(816) > tosp(812)
Block header dump: 0x3f8dea78
Object id on Block? Y
seg/obj: 0x155b452 csc: 0x05.7b2b4ee6 itc: 3 flg: E typ: 1 - DATA
brn: 0 bdba: 0x3f8dde0c ver: 0x01
inc: 0 exflg: 0

Note the DBA value reported in the trace file DBA = 1066265208
Convert this to find the file number and block number having issue

Sql> Select dbms_utility.data_block_address_file('1066265208') from dual;

DBMS_UTILITY.DATA_BLOCK_ADDRESS_FILE('1066265208')
--------------------------------------------------
254

Sql> Select dbms_utility.data_block_address_block('1066265208') from dual;

DBMS_UTILITY.DATA_BLOCK_ADDRESS_BLOCK('1066265208')
---------------------------------------------------
911992


Run dbverify on the datafile containing the table

$ dbv file=<location of datafile> blocksize=<db_block_size>

Corruption would be reported on the block.

If you have an Rman backup do a Rman block recovery (Take the file number and block number affected from the trace file)

Rman> Blockrecover datafile <no> block <block number>;

Or

If you have a user managed backup you can do an restore and recovery from good copy of the problematic datafile

Option b> Backup is not available

If no backups are available then use event 10231 at session level to create a salvage table

SQL> Alter session set events '10231 trace name context forever, level 10';
SQL> Create table <owner>.salvage_table as select * from <Corrupted table>;

Rename the Original table to old.

Rename salvage table to Original table name

How to resolve when Smon terminates the instance due to Ora-00600[13013]

If Smon is terminating the instance then.

Set event 10513 and startup the database
event="10513 trace name context forever, level 2"

SQL> Startup mount;
SQL> Show parameter event
SQL> Alter datatabase open;

Identify the object involved using information from Section 1.

How to resolve the issue if the object involved belongs to system tablespace

System objects are very important.
Please open a Service request with Oracle support if system tables are involved.

Reference: MOS note id - 816784.1

Manual Oracle Database Creation

This document briefs about the step by step procedure for creating a database on unix environment.

Before starting, it is best to have the relevant environment variables set (ORACLE_SID, ORACLE_HOME, PATH, etc...). Best to have this setup in a .profile file.

Also create all the directory structures required.

Step 1: Make an init<SID>.ora in your $ORACLE_HOME/dbs directory. To simplify, you can copy init.ora to init<SID>.ora and modify the file.

            Path names, file names, and sizes will need to be modified

            Example parameter settings:

            db_block_size=8192

            db_cache_size=52428800

            background_dump_dest=/u01/32bit/app/oracle/product/9.0.1/bdump

            core_dump_dest=/u01/32bit/app/oracle/product/9.0.1/cdump

            user_dump_dest=/u01/32bit/app/oracle/product/9.0.1/udump

            timed_statistics=TRUE

            control_files=("/u01/rbdb1/control_01.ctl", "/u01/rbdb1/control_02.ctl")

            db_name=rbdb1

            shared_pool_size=52428800

            sort_area_size=524288

            undo_management=AUTO

            undo_tablespace=UNDOTBS

Step 2: Run the following sqlplus command to connect to the database:

            ]$ sqlplus '/ as sysdba'

Step 3: Startup up the database in NOMOUNT mode:

            SQL> startup nomount

Step 4: Create the Database by issuing the following in the SQL prompt:

            Path names, file names, and sizes will need to be modified

            CREATE DATABASE <db_name>

            MAXLOGFILES 255

            MAXINSTANCES 1

            MAXDATAFILES 256

            MAXLOGHISTORY 256

            DATAFILE '/u01/oracle/rbdb1/system_01.dbf' SIZE 400M REUSE

            SYSAUX DATAFILE '/u01/oracle/rbdb1/sysaux_01.dbf' SIZE 500M REUSE

UNDO TABLESPACE "UNDOTBS" DATAFILE '/u01/oracle/rbdb1/undotbs_01.dbf'

SIZE 200M REUSE AUTOEXTEND ON NEXT 5120K MAXSIZE UNLIMITED

            CHARACTER SET US7ASCII

            LOGFILE GROUP 1 ('/u01/oracle/rbdb1/redo1_01.dbf') SIZE 100M REUSE,

            GROUP 2 ('/u01/oracle/rbdb1/redo1_02.dbf') SIZE 100M REUSE;

Sysaux data file required for database version 10g and above.

Step 5: Create a Temporary Tablespace :

            Path names, file names, and sizes will need to be modified

CREATE TEMPORARY TABLESPACE "TEMP" TEMPFILE '/u01/oracle/rbdb1/temp_01.dbf'

            SIZE 40M REUSE AUTOEXTEND ON NEXT  640K MAXSIZE UNLIMITED

            EXTENT MANAGEMENT LOCAL;

            ALTER DATABASE DEFAULT TEMPORARY TABLESPACE "TEMP";

Step 6: Run the following scripts as sys to create data dictionary views and tables.

@?/rdbms/admin/catalog.sql;

@?/rdbms/admin/catblock.sql;

@?/rdbms/admin/catproc.sql;

@?/rdbms/admin/catoctk.sql;

Step 7: Run the following scripts as system to create product user profile and command line help.

@?/sqlplus/admin/pupbld.sql;

@?/sqlplus/admin/help/hlpbld.sql helpus.sql;

Step 8: Put the database in archivelog mode.

SQL> alter database archivelog;

Step 9: Reset the sys and system password and create password file if required.

           

SQL> ALTER USER SYS IDENTIFIED BY <password>;

            SQL> ALTER USER SYSTEM IDENTIFIED BY <password>;

Step 10: Backup created database

Step 11: Create, configure and start the listener.

Step 12: Schedule the required backup and monitoring scripts in cron