Recovery lost undo tablespace and Redo log

Recovery undo tablespace
[email protected]> shutdown
Database closed.
Database dismounted.
ORACLE instance shut down.e
[email protected]> exit
Disconnected from Oracle9i Enterprise Edition Release 9.2.0.1.0 - Production
With the Partitioning, OLAP and Oracle Data Mining options
JServer Release 9.2.0.1.0 - Production
[ora920@tkyte-pc-isdn ora920]$ ls
control01.ctl cwmlite01.dbf indx01.dbf redo02.log redo0B.log temp01.dbf
users01.dbf
control02.ctl drsys01.dbf odm01.dbf redo03.log redo0C.log tools01.dbf
xdb01.dbf
control03.ctl example01.dbf redo01.log redo0A.log system01.dbf undotbs01.dbf
[ora920@tkyte-pc-isdn ora920]$ mv undotbs01.dbf undotbs01.dbf.xxx
[ora920@tkyte-pc-isdn ora920]$ sqlplus /nolog
SQL*Plus: Release 9.2.0.1.0 - Production on Sat Sep 28 08:33:29 2002
Copyright (c) 1982, 2002, Oracle Corporation. All rights reserved.
idle> connect / as sysdba
Connected to an idle instance.
idle> startup
ORACLE instance started.
Total System Global Area 143725064 bytes
Fixed Size 451080 bytes
Variable Size 109051904 bytes
Database Buffers 33554432 bytes
Redo Buffers 667648 bytes
Database mounted.
ORA-01157: cannot identify/lock data file 2 - see DBWR trace file
ORA-01110: data file 2: '/usr/oracle/ora920/OraHome1/oradata/ora920/undotbs01.dbf'
idle> show parameter undo
NAME TYPE VALUE
undo_management string AUTO
undo_retention integer 10800
undo_suppress_errors boolean FALSE
undo_tablespace string UNDOTBS1
idle> alter system set undo_management = manual scope=spfile;
System altered.
Note: disabling the undo tablespace here, this'll let us go back to "rollback segments"
and we'll use the system RBS to get back on our feet
idle> shutdown
ORA-01109: database not open
Database dismounted.
ORACLE instance shut down.
idle> exit
Disconnected from Oracle9i Enterprise Edition Release 9.2.0.1.0 - Production
With the Partitioning, OLAP and Oracle Data Mining options
JServer Release 9.2.0.1.0 - Production
[ora920@tkyte-pc-isdn ora920]$ !sql
sqlplus /nolog
SQL*Plus: Release 9.2.0.1.0 - Production on Sat Sep 28 08:35:34 2002
Copyright (c) 1982, 2002, Oracle Corporation. All rights reserved.
idle> connect / as sysdba;
Connected to an idle instance.
idle> startup
ORACLE instance started.
Total System Global Area 143725064 bytes
Fixed Size 451080 bytes
Variable Size 109051904 bytes
Database Buffers 33554432 bytes
Redo Buffers 667648 bytes
Database mounted.
ORA-01157: cannot identify/lock data file 2 - see DBWR trace file
ORA-01110: data file 2: '/usr/oracle/ora920/OraHome1/oradata/ora920/undotbs01.dbf'
Note: we still have to get rid of that thing..
idle> alter database datafile '/usr/oracle/ora920/OraHome1/oradata/ora920/undotbs01.dbf'
2 offline drop;
Database altered.
idle> alter database open;
Database altered.
idle> drop tablespace undotbs1;
Tablespace dropped.
idle> create UNDO tablespace undotbs1
2 datafile '/usr/oracle/ora920/OraHome1/oradata/ora920/undotbs01.dbf' size 25m
3 autoextend on next 1m maxsize 1024m;
Tablespace created.
idle> alter system set undo_management = auto scope=spfile;
System altered.
Now, we've put the undo tablespace "back" by creating a new one. Just bounce...
idle> shutdown
Database closed.
Database dismounted.
ORACLE instance shut down.
idle> exit
Disconnected from Oracle9i Enterprise Edition Release 9.2.0.1.0 - Production
With the Partitioning, OLAP and Oracle Data Mining options
JServer Release 9.2.0.1.0 - Production
[ora920@tkyte-pc-isdn ora920]$ !sql
sqlplus /nolog
SQL*Plus: Release 9.2.0.1.0 - Production on Sat Sep 28 08:40:51 2002
Copyright (c) 1982, 2002, Oracle Corporation. All rights reserved.
idle> connect / as sysdba;
Connected to an idle instance.
idle> startup
ORACLE instance started.
Total System Global Area 143725064 bytes
Fixed Size 451080 bytes
Variable Size 109051904 bytes
Database Buffers 33554432 bytes
Redo Buffers 667648 bytes
Database mounted.
Database opened.
idle> show parameter undo
NAME TYPE VALUE
undo_management string AUTO
undo_retention integer 10800
undo_suppress_errors boolean FALSE
undo_tablespace string UNDOTBS1
idle>
and we are right back where we started from
RECOVERY REDO TABLESPACE
STARTUP MOUNT;
RESTORE DATABASE;
RECOVER DATABASE UNTIL SEQUENCE $v_seq THREAD 1;
ALTER DATABASE OPEN RESETLOGS;

[email protected] wrote:
just ignore first one like title
Alter database open resetlog is not necessary to open database ?
Regards
kmphttp://download.oracle.com/docs/cd/B19306_01/backup.102/b14191/osrecov.htm#i1007426
About Opening with the RESETLOGS Option
The RESETLOGS option is always required after incomplete media recovery or recovery using a backup control file.
You did not do an incomplete media recovery nor a recovery using a backup control file.

Similar Messages

What is the difference between undo tablespace and online redo log files.

what is the difference between undo tablespace and online redo log files. I am confused
as per my knowledge undo tablespace is used to store the undo information when a table is being updated so that, just incase we need to rollback a transaction we know what was present in the table earlier.
when a transaction fails the SMON performs the rollback of the data.
This undo data is stored in the undo tablespace and read consistency if any is enforced.
is my understanding till here correct?
Now, can this undo data/before image not be stored in the redo log buffer and online redolog files?
can redo-log files not store this information?
in fact, is it that when undo tablespaces exist in a database, the undo data/before image is stored in both the undo tablespace and also the redo log files?
kindly clarify my doubt.
thank you.

This question has been asked many times before. The answer is always the same.
Yes, redo contains the before image of data (and the after-image). Therefore, it **COULD** be used to roll back a transaction.
BUT... Redo is written sequentially. Using it to rollback your transaction would involve reading through all the redo written by maybe thousands of other people. It would be painfully slow.
Your transaction is, however, directly linked to just the UNDO that it generates (which is JUST the before image of the data). So, your undo is your undo and doesn't share space with anyone else's undo. Therefore, using it to roll back YOUR transaction is fast.
The fact that undo is only the before image of the data also makes it faster than wading through a sea of before and AFTER images as you'd find in redo. About twice as fast, in fact, since there's half the data. Roughly.
Redo also gets written and flushed to disk whenever there's a commit, 3 seconds are up or too much (1MB, actually) redo gets generated between flushes caused by other factors. Your redo gets flushed when those things happen, even if you haven't actually committed your transaction. And redo logs recycle themselves, meaning that your redo -even if your transaction hasn't been committed yet- can be over-written by later transactions. Try rolling back when that's happened, if redo was the source of your rollback data!
Undo, however, cannot be over-written if the transaction has not been committed. Ever. If you don't commit for three years, there will be three years' undo stored in your database (assuming you had the space, of course!).
I could go on, but that will do. Redo is there fore RECOVERY, after catastrophe. Undo is there for read-consistency (and the occasional change of mind). Two different functions. Two different mechanisms. Each one highly tuned to doing what it does, why it does it, most efficiently and effectively.

Chmod 640 (Datafile,UNDO,TEMP Tablespace, Controlfile, Redo Log Files, Arch

If i change the permssion of these file to 640, will this break any thing?
what are the suggested permission of Oracle files and directories?

here i am doing to secure my DBs Just doing research that it dont break any thing
These are the permission i am going to change in my DBs , any suggestion?
chmod 750 /u02/oradata/sid_name
Chmod 640 (Datafile,UNDO,TEMP Tablespace, Controlfile, Redo Log Files, Archivelogs)
chmod 644 (alert Logs, init.ora files, config.ora files)
Chmod 640 $ORACLE_HOME/rdbms/admin/utlpwdmg.sql
Verify umask = 022 - type "umask" - should return 022; if not, modify in .profile
Verify all files are readable--run the following:
select file_name, status from dba_data_files where status != 'AVAILABLE'--should return 0 rows
SUN - ls -al /var/opt/oracle/oratab = should be owner=oracle group=dba
IF NOT, OPEN SR TO UNIX TEAM TO CHANGE
Verify oraInst.loc - look at /u01/app/oracle/security/*.info - setting A271-
/var/opt/oracle/oraInst.loc - owned by oracle:dba
*IF NOT, OPEN SR TO UNIX TEAM TO CHANGE
Verify ownership of $ORACLE_HOME/network/admin/listener.ora,$ORACLE_HOME/network/admin/tnsnames.ora
= oracle:dba
*IF NOT, OPEN SR TO UNIX TEAM TO CHANGE
Verification:
1. run gsd331 scan and verify fixed--
execute /u01/app/oracle/security/orashc -m -a *output will go to [email protected]
BACKOUT:
Change permission back to 755

When occurs crash recovery,why use active online redo log not archived log?

If current redo log had archived, but it's still 'ACTIVE'. As we all know, archived log is just an archived copy of the current redo log which is still 'ACTIVE', they have the same data. But why use active online redo log not archived log for crash recovery?(I think, if crash recovery can use archived log, then whether the online redo log is 'ACTIVE' or not, it can be overwritten)
Quote:
Re: v$log : How redo log file can have a status ACTIVE and be already archived?
Hemant K Chitale
If your instance crashes, Oracle attempts Instance Recovery -- reading from the Online Redo Logs. It doesn't need ArchiveLogs for Instance Recovery.
TanelPoder
Whether the log is already archived or not doesn't matter here, when the instance crashes, Oracle needs some blocks from that redolog. Archivelog is just an archived copy of the redolog, so you could use either the online or achive log for the recovery, it's the same data in there (Oracle reads the log/archivelog file header when it tries to use it for recovery and validates whether it contains the changes (RBA range) in it what it needs).

Aman.... wrote:
John,
Are you sure that the instance recovery (not the media recovery) would be using the archived redo logs? Since the only thing that would be lost is the isntance, there wouldn't be any archived redo log generated from the Current redo log and the previous archived redo logs, would be already checkpointed to the data file, IMHO archived redo logs won't participate in the instance recovery process. Yep, shall watch the video but tomorrow .
Regards
Aman....
That's what I said. Or meant to say. If Oracle used archivelogs for instance recovery, it would not be possible to recover in noarchive log mode. So recovery relies exclusively on the online log.
Sorry I wasted your time, I'll try to be less ambiguous in future

Best RAID configuration for storing Datafiles and Redo log files

Database version:10gR2
OS version: Solaris
Whis is the best RAID level for storing Datafiles and Redo log files?

Oracle recommends SAME - Stripe And Mirror Everything.
In the RAC Starter Kit documentation, they specifically recommend not using RAID5 for things like voting disk and so on.
SAN vendors otoh claims that their RAID5 implementations are as fast as RAID10. They do have these massive memory caches...
But I would rather err on the safer side. I usually insist on RAID10 - and for those databases that I do not have a vested interest in (other than as a DBA), and owners, developers and management accept RAID5, I put the lead pipe away and do not insist on having it my way. :-)

I lost my password and cannot log on to my MacBook Pro. MacOS X window opens upon startup, with my log on name, requesting password, but I cannot remember it. Is there a way to bypass this window and reset my password? Cannot get to System Preferences

I lost my password and cannot log on to my MacBook Pro. MacOS X window opens upon startup, with my log on name, requesting password, but I cannot remember it. Is there a way to bypass this window and reset my password? Cannot get to System Preferences or Apple Menu
Thanks!

Yes.
https://discussions.apple.com/thread/4913069

Changing names of datafiles, tempfiles and redo log files

DB version:10g Release 2
Can i use
ALTER DATABASE RENAME FILE ...command to rename datafiles, tempfiles and redo log files?

ScottsTiger wrote:
DB version:10g Release 2
Can i use
ALTER DATABASE RENAME FILE ...command to rename datafiles, tempfiles and redo log files?Why not check the Fine Manual found at tahiti.oracle.com?
Please note that when you use this command, you are doing nothing to the actual files on the OS. You are simply changing the db's knowledge of them, as stored in the control file.

Undo tablespace and instance recovery

Is UNDO tablespace is mandatory during instance recovery. ?
Suppose my undo tablespace has some active transaction and instance crashes making undo tablespace inaccessible.
Will database search for that undo tablespace during startup or I can simply create a new one and set as new undo tablespace ?
With Regards
Amt

Hi,
>>I am actually confused
Keep in mind that If an Oracle instance crashes, any changes that are made in the SGA are not written to the data files. When you restart the instance, the SMON background process automatically performs instance recovery by performing the following tasks:
• Rolling forward changes that are made in the online redo log files but not in the data files. Since all the committed transactions are written to the online redo log files, these are successfully recovered as result of rolling forward changes from the online redo log files to the data files.
• Opening the database. After the database is opened, users can log on and access any data that is not locked by un-recovered transaction.
• Rolling back all the uncommitted transactions.
In resume, during database recovery, undo records are used to undo any uncommitted changes applied from the redo log to the datafiles.
But if your UNDO tablespace crashed, then you will need recover it, using steps like
1) shutdown abort (If the instance yet is up)
2) cp -a /backup/undo01.dbf /u01/oradata (restore the latest recent backup file)
3) startup mount
4) recover database or recover datafile '/u01/oradata/undo01.dbf'
5) alter database open;
In some cases, re-create it, also resolve the problem:
http://asktom.oracle.com/pls/asktom/f?p=100:11:0::::P11_QUESTION_ID:5669213349582
Missing UNDO tablespace in restore backup
>>I checked in test setup and it is actually waiting for missing UNDO tablespace.
Which exactly test you are doing?
Cheers

Recover database without controlfile and redo logs

Hi guys,
I am doing a testing with an Oracle Database 11.1.0.7.0, I want recover a database in this scenario without using RMAN:
-All controlfiles are missing
-All redo logs are missing
-I have a Backup Controlfile To Trace Resetlogs (bkp_controlfile.sql)
-The database is in archivelog mode
-The database was created with OMF (Oracle Managed Files)
So I have done this steps:
1) When the database was opened I rename all controlfiles and all redo logs
2) Shutdown Abort
3) I run the bkp_controlfile.sql, here I have a problem...
The database put in NOMOUNT, the controlfile was created and started the RECOVER DATABASE USING BACKUP CONTROLFILE, but when run ALTER DATABASE OPEN RESETLOGS; appear this:
ERROR at line 1:
ORA-01113: file 1 needs media recovery
ORA-01110: data file 1:
'/u02/app/oracle/oradata/OMF/datafile/o1_mf_system_68hzcb2z_.dbf'I wasn´t expect this because I don´t want recover a datafile, I only want open with resetlogs.
Any suggestion to help me?
Thanks a lot.

Excelent! Thanks for your answers Markus and Hemant.
In conclusion...
- If we have all redo logs availables we can recreate the control file and recover the database without any problems using backup controlfile to trace noresetlogs*.
- if we haven´t all redo logs availables, there are 2 situations:
1) If the database shutdown properly:_ We will be able to open the database using recover database using backup controlfile until cancel*.
2) If the database doesn´t shutdown properly:_ We won´t be able to open the database with only a backup controlfile to trace.
With all this I close this thread. Was very good experience.
If anyone would add something will be welcome.
Thanks for all
I wish add the results of one of my tests: if I did all the steps in only one session of sqlplus I can shutdown properly the database, but if do the shutdown immediate* in a new session I can´t shutdown properly the database. Here I post the output:
ALL IN ONE SESSION*
[oracle@prueba ~]$ $ORACLE_HOME/bin/sqlplus / as sysdba
SQL*Plus: Release 11.1.0.7.0 - Production on Wed Sep 22 13:58:10 2010
Copyright (c) 1982, 2008, Oracle. All rights reserved.
Connected to:
Oracle Database 11g Enterprise Edition Release 11.1.0.7.0 - Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
SQL> ALTER SYSTEM SWITCH LOGFILE;
System altered.
SQL> SHUTDOWN IMMEDIATE
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> STARTUP
ORACLE instance started.
Total System Global Area 631914496 bytes
Fixed Size                  1315224 bytes
Variable Size             377491048 bytes
Database Buffers          247463936 bytes
Redo Buffers                5644288 bytes
Database mounted.
Database opened.
SQL> SHUTDOWN IMMEDIATE
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> @/home/oracle/bkp_controlfile.sql
ORACLE instance started.
Total System Global Area 631914496 bytes
Fixed Size                  1315224 bytes
Variable Size             377491048 bytes
Database Buffers          247463936 bytes
Redo Buffers                5644288 bytes
Control file created.
SQL> RECOVER DATABASE USING BACKUP CONTROLFILE UNTIL CANCEL;
ORA-00279: change 398764 generated at 09/22/2010 14:09:49 needed for thread 1
ORA-00289: suggestion :
/u02/app/oracle/flash_recovery_area/OMF/archivelog/2010_09_22/o1_mf_1_40_%u_.arc
ORA-00280: change 398764 for thread 1 is in sequence #40
Specify log: {<RET>=suggested | filename | AUTO | CANCEL}
CANCEL
Media recovery cancelled.
SQL> ALTER DATABASE OPEN RESETLOGS;
Database altered.
SQL> ALTER TABLESPACE TEMP ADD TEMPFILE '/u02/app/oracle/oradata/OMF/datafile/o1_mf_temp_69n3z3vv_.tmp' SIZE 50331648 REUSE AUTOEXTEND ON NEXT 655360 MAXSIZE 32767M;
Tablespace altered.
SQL>
ALL IN DIFERENT SESSIONS*
[oracle@prueba ~]$ $ORACLE_HOME/bin/sqlplus / as sysdba
SQL*Plus: Release 11.1.0.7.0 - Production on Wed Sep 22 13:55:47 2010
Copyright (c) 1982, 2008, Oracle. All rights reserved.
Connected to:
Oracle Database 11g Enterprise Edition Release 11.1.0.7.0 - Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
SQL> ALTER DATABASE BACKUP CONTROLFILE TO TRACE AS '/home/oracle/bkp_controlfile.sql' RESETLOGS;
Database altered.
SQL> SHUTDOWN IMMEDIATE
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> STARTUP MOUNT
ORACLE instance started.
Total System Global Area 631914496 bytes
Fixed Size                  1315224 bytes
Variable Size             377491048 bytes
Database Buffers          247463936 bytes
Redo Buffers                5644288 bytes
Database mounted.
SQL> ALTER DATABASE ARCHIVELOG;
Database altered.
SQL> ALTER DATABASE OPEN;
Database altered.
SQL> ALTER SYSTEM SWITCH LOGFILE;
System altered.
SQL> ALTER SYSTEM SWITCH LOGFILE;
System altered.
SQL> exit
Disconnected from Oracle Database 11g Enterprise Edition Release 11.1.0.7.0 - Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
[oracle@prueba ~]$ $ORACLE_HOME/bin/sqlplus / as sysdba
SQL*Plus: Release 11.1.0.7.0 - Production on Wed Sep 22 13:58:10 2010
Copyright (c) 1982, 2008, Oracle. All rights reserved.
Connected to:
Oracle Database 11g Enterprise Edition Release 11.1.0.7.0 - Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
SQL> SHUTDOWN IMMEDIATE
ORA-00210: cannot open the specified control file
ORA-00202: control file: '/u02/app/oracle/oradata/OMF/controlfile/o1_mf_69n3x6n5_.ctl'
ORA-27041: unable to open file
Linux Error: 2: No such file or directory
Additional information: 3

XE11: sysaux & undo tablespaces and files

Hello,
does anyone recognized the mixed names of sysaux and undo tablespaces?
If i use:
SQL> SELECT file_name, tablespace_name, ROUND(bytes/1024000) MB
SQL> FROM dba_data_files
SQL> ORDER BY 1;
then i will get:
FILE_NAME TABLESPACE MB
C:\ORACLEXE\APP\ORACLE\ORADATA\XE\SYSAUX.DBF UNDOTBS1 26
C:\ORACLEXE\APP\ORACLE\ORADATA\XE\SYSTEM.DBF SYSTEM 369
C:\ORACLEXE\APP\ORACLE\ORADATA\XE\UNDOTBS1.DBF SYSAUX 666
C:\ORACLEXE\APP\ORACLE\ORADATA\XE\USERS.DBF USERS 102
The file SYSAUX.DBF points to tablespace UNDOTBS1 and
the file UNDOTBS1.DBF points to tablespace SYSAUX
Could this cause a Problem ?
Can this be solved?
This is only in the windows-version, not in the linux-version.
Best reagrds
AK

Hello,
i did the following:
SQLPLUS:
SHUTDOWN IMMEDIATE;
AS ADMINISTRATOR:
COPY C:\oraclexe\app\oracle\oradata\XE\SYSAUX.DBF C:\oraclexe\app\oracle\oradata\XE\UNDOTBS2.DBF
COPY C:\oraclexe\app\oracle\oradata\XE\UNDOTBS1.DBF C:\oraclexe\app\oracle\oradata\XE\SYSAUX2.DBF
SQLPLUS:
STARTUP MOUNT:
ALTER DATABASE RENAME FILE 'C:\oraclexe\app\oracle\oradata\XE\SYSAUX.DBF' TO 'C:\oraclexe\app\oracle\oradata\XE\UNDOTBS2.DBF';
ALTER DATABASE RENAME FILE 'C:\oraclexe\app\oracle\oradata\XE\UNDOTBS1.DBF' TO 'C:\oraclexe\app\oracle\oradata\XE\SYSAUX2.DBF';
ALTER DATABASE OPEN;
SHUTDOWN IMMEDIATE;
AS ADMINISTRATOR:
COPY C:\oraclexe\app\oracle\oradata\XE\SYSAUX2.DBF C:\oraclexe\app\oracle\oradata\XE\SYSAUX.DBF (overwrite y)
COPY C:\oraclexe\app\oracle\oradata\XE\UNDOTBS2.DBF C:\oraclexe\app\oracle\oradata\XE\UNDOTBS1.DBF (overwrite y)
SQLPLUS:
STARTUP MOUNT:
ALTER DATABASE RENAME FILE 'C:\oraclexe\app\oracle\oradata\XE\SYSAUX2.DBF' TO 'C:\oraclexe\app\oracle\oradata\XE\SYSAUX.DBF';
ALTER DATABASE RENAME FILE 'C:\oraclexe\app\oracle\oradata\XE\UNDOTBS2.DBF' TO 'C:\oraclexe\app\oracle\oradata\XE\UNDOTBS1.DBF';
ALTER DATABASE OPEN;
SHUTDOWN IMMEDIATE;
AS ADMINISTRATOR:
DEL C:\oraclexe\app\oracle\oradata\XE\SYSAUX2.DBF
DEL C:\oraclexe\app\oracle\oradata\XE\UNDOTBS2.DBF
SQLPLUS:
STARTUP
RMAN:
REPORT SCHEMA;
Spooling started in log file: switch.txt
Recovery Manager11.2.0.2.0
RMAN>
Report of database schema for database with db_unique_name XE
List of Permanent Datafiles
===========================
File Size(MB) Tablespace RB segs Datafile Name
1 360 SYSTEM *** C:\ORACLEXE\APP\ORACLE\ORADATA\XE\SYSTEM.DBF
2 650 SYSAUX *** C:\ORACLEXE\APP\ORACLE\ORADATA\XE\SYSAUX.DBF
3 25 UNDOTBS1 *** C:\ORACLEXE\APP\ORACLE\ORADATA\XE\UNDOTBS1.DBF
4 100 USERS *** C:\ORACLEXE\APP\ORACLE\ORADATA\XE\USERS.DBF
List of Temporary Files
=======================
File Size(MB) Tablespace Maxsize(MB) Tempfile Name
1 20 TEMP 32767 C:\ORACLEXE\APP\ORACLE\ORADATA\XE\TEMP.DBF
RMAN>
Recovery Manager complete.
It's not looking elegant but it's working.
Is there a other way?
Best regards.

Partial Recovery - Skip UNDO Tablespace

Hi,
I was performing a partial database recovery using skip tablespace option using RMAN. I was wondering if I can skip undo tablespace.
I was not able to conclude whether I can do that? If not, why?
As per my understanding,
1. Datafiles are restored - If they have any uncommited data, then archive logs which will be applied for media recovery, will have the undo data to perform those roll backward.
2. While performing media reccovery using archive logs, it will generate it's own undo data.
Why do we need the stale undo data (generated till datafiles restoration point)?
Thanks,
Janak Agrawal

Soli,
Thread that you have specified, talks about datafiles which does not have any uncommitted data (As the database was normally shutdown). In this case, we can drop and recreate the undo tablespace.
But I am talking about a past point-in-time recovery using RMAN, where the datafiles which will be restored may have the uncommitted data. To rollback these uncommited trnasactions, will we have data in next archivelogs, which will be used for media recovery or the data (needed to rollback) will have only in undo tablespace. Let me give you an example.
At 9 am I want to restore the datbase till 8.15 AM. Full backup is available till 8 AM and then from 8 to 8:15 arvhive logs are available. While doing recovery, datafiles will be restored till 8 AM. If at 8 AM there is some uncommitted data in datafiles, will it require data from undo tablespace to rollback or first archive log after 8 AM w'd take care of roll back? If archive logs can take care of rollback, why can't I skip the undo tablespace while doing recovery?
Santosh,
As you mentioned, UNDO data will require for read-consistency. But the same data will be available in archive logs (which will require after datafiles restore) which can generate their own UNDO data.
Please clarify. I am sorry if I am missing anything here.
Thanks,
Janak Agrawal

Can I use old dbf, ctl and redo.log files on re-installation? URGENT

Hello,
DB: 10.2.0.1.0
Because of some reasons I am reinstalling Oracle DB in our test server.
Prior to install I removed all files under ORACLE_HOME.
But I am keeping my old datafiles, redo.log & cntrl file.
Is it ok that to define same Database files location where my old files existed?
we have dbf, redo.log, ctl files in that location.
I wonder if I used the same files than I probably do not need to create new data files and also do not need to required import data. This is our test database.
D

If all database files are intact then you can reinstall the Oracle software and just start the pre-existing database. All the files would include the spfile or a copy of the init.ora.
In fact that is one way of doing a version upgrade by overlaying $ORACLE_HOME with the new version. We like to install in a new home since we usually run multiple versions at one time and then start the existing databases using the new release and running the database upgrade scripts one at a time when the release proves stable.
HTH -- Mark D Powell --

Database in log archive mode and redo log file in mode not archive

Hello,
I have a dabatabase running in archive log mode, recently changed, I have 5 redo log groups and one of them (the current one) shows in the v$log view, that ARC: NO, I mean, no archiving. All redo logs except it shows ARC:Yes
What does it mean?
Am I going to have problems with this redo log file?
Thanks

If you do describe on v$log, you'll find that the full column name is Archived (meaning is it archived yet?).
You could try alter system switch logfile and then check v$log again a few times after.
Use the docu for finding out more about v$ views and so on
http://www.oracle.com/pls/db102/print_hit_summary?search_string=v%24log

Hierarchial Queries and Redo log files

Hi,
I'm running a hierarchial query (start with, connect by prior, etc.).
The query takes a couple of minutes and apparently is filling up the archive files
(I assume it comes from the redo log files).
Question:
1. Does it make sense that a hierarchial query should so fill up the redo log files (It seems as if all the 'intermediate' results are being written there).
2. What do you suggest I do ??
Thanks,
David

What do you suggest I do ??Post your query and the execution plan or the trace file from tkprof.
How to do that is explained in this thread;
How to post a SQL statement tuning request HOW TO: Post a SQL statement tuning request - template posting

Undo Tablespace and Temporary Tablespace - autoextend ?

- In general, should I allow the Undo Tablespace to grow (autoextend)?
- In general, should I allow the Temporary Tablespace to grow (autoextend)?

The size of undo tablespace should always keeps in mind otherwiase you eill get ORA-1555 or out of space errors.
This paper is to help DBA’s in calculating the size of UNDO tablespace by using a simple formula.
It is tough to know about the number of transactions and subsequently number of rows changed per second.
So I suggest having a “big undo tablespace” to start with and based on load, after doing some calculations and resize your UNDO tablespace.
In my case one of the applications was going to production (live), and I had no idea that how many transactions will happen against this database. All what I was told that there will be optimum (transactional) activity on this database.
So I started with UNDO tablespace with size of 3GB and datafiles with autoextend “on” .
Note:
In production, you must be very careful in using this (autoextend on) as the space may grow to inifinity very fast. So my advice is either dont use this option, or use with "maxsize" or continuously monitor space (which is tough).
I month later, I noticed the activity from V$undostat.
Here is the step by step approach:
Step 1: Longest running query.
SQL> select max(maxquerylen) from v$undostat;
MAX(MAXQUERYLEN)
1793
This gives you ideal value for UNDO_RETENTION. To be on the safer size you should add few more seconds to get the right value. So in my case, the size of undo retention should be say 2000 secs.
Step 2: Size of UNDO tablespace.
Size of UNDO needed = UNDO_RETENTION x [UNDO block Generation per sec x DB_BLOCK_SIZE] + Overhead(30xDB_BLOCK_SIZE)
Out of these we know UNDO_RETENTION and DB_BLOCK_SIZE
All we need is to find out “UNDO Blocks per second”
Which can be easily fetched from v$undostat
SQL> SELECT (SUM(undoblks))/ SUM ((end_time - begin_time) * 24*60*60) "UPS"
2 FROM v$undostat;
UPS
8.11985583
V$undostat stores data for every 10 mins and begin/end times are start/end time of those intervals. We multiplied it with 24*60*60 because the difference between two dates will be in days and to get to seconds, we need it to multiply with 24hrs*60mins*60secs
So now we have all the values needed.
Undo size needed = [8.12 x 2000 x 8192] + [30 x 8192] = 133283840 bytes = 127.11 MB

Recovery lost undo tablespace and Redo log

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