Delete old and unused Archived Redo Log Files

Hello forum!
My db was in ARCHIVELOG mode and It created 9GB of archived redo log files.
Now I put the db in NOARCHIVELOG mode, can I delete all the ARLF? am I sure that the DB never need those files in the future?
If yes, how can I delete them? I will use 'del' operative system command?
In addition, I found this command:
SQL>alter database open resetlogs;
is it useful for my purpose?
thank you!

You are safe to remove those archivelog files if you altered your database to no archive log mode. Just remove them from OS level
Please bear in mind that database in no archivelog mode will lost data in the event of disaster.
SQL>alter database open resetlogs;Doesn't help in your situation, it's use to bring up database after incomplete recovery.

Similar Messages

Hoping for a quick response : EXP and Archived REDO log files

I apologize in advance if this question has been asked and answered 100 times. I admit I didn't search, I don't have time. I'm leaving on vacation tomorrow, and I need to know if I'm correct about something to do with backup / restore.
we have 10g R2 running a single instance on a single server. The application vendor has "embedded" oracle with their application. The vendor's backup is a batch file using EXP - thus:
exp system/xpwdxx@db full=y file=D:\Orant\admin\db\EXP\db_full.dmp log=D:\Orant\admin\db\EXP\db_full.txt direct=y compress=y
This command is executed nightly at midnight. The files are then backed up by our nightly backup to offsite storage media.
Te database is running in autoarchive mode. The problem is, the archived redo files filled the drive they were being stored on, and it is the drive the database is on. I used OS commands to move 136G of archived redo logs onto other storage media to free the drive.
My question: Since the EXP runs at midnight, when there is likely NO activity, do I need to run in AutoArchive Mode? From what I have read, you cannot even apply archived redo log files to this type of backup strategy (IMP) Is that true? We are ok losing changes since our last EXP. I have read a lot of stuff about restoring consistent vs. inconsistent, and just need to know: If my disk fails, and I have to start with a clean install of Oracle and nothing else, can I IMP this EXP and get back up and running as of the last EXP? Or do I need the autoarchived redo log files back to July 2009 (136G of them).
Hoping for a quick response
Best Regards, and thanks in advance
Bruce Davis

Bruce Davis wrote:
Amardeep Sidhu
Thank you for your quick reply. I am reading in the other responses that since I am using EXP without consistent=y, I might not even have a backup. The application vendor said that with this dmp file they can restore us to the most recent backup. I don't really care for this strategy as it is untested. I asked them to verify that they could restore us and they said they tested the dmp file and it was OK.
Thank you for taking the time to reply.
Best Regards
BruceThe dump file is probably ok in the sense it is not corrupted and can be used in an imp operation. That doesn't mean the data in it is transactionally consistent. And to use it at all, you have to have a database up and running. If the database is physically corrupted, you'll have to rebuild a new database from scratch before you can even think about using your dmp file.
Vendors never understand databases. I once had a vendor tell me that Oracle's performance would be intolerable if there were more than 5 concurrent connections. Well, maybe in HIS product ..... Discussions terminated quickly after he made that statement.

Recover Database is taking more time for first archived redo log file

Hai,
Environment Used :
Hardware : IBM p570 machine with P6 processor Lpar of .5 CPU and 2.5 GB Ram
OS : AIX 5.3 ML 07
Cluster: HACMP 5.4.1.2
Oracle Version: 9.2.0.4 RAC
SAN : DS8100 from IBM
I have used flash copy option to copy the database from production to test machine. Then tried to recover the database to an consistent state using the command "recover automatic database until cancel". System is taking long time and after viewing the alert log it was found that, for the first time, if it is reading all the datafiles and it is taking 3 seconds for each datafile. Since i have more than 500 datafiles, it is nearly taking 25 mins for applying the first archived redo log file. All other log files are applied immeidately without any delay. Any suggession to improve the speed will be highly appreciated.
Regards
Sridhar

After chaning the LPAR settings with 2 CPU and 5GB RAM, the problem solved.

Is it possible to use Archive Redo log file

Hi friends,
My database is runing in archive log mode.I had taken cold backup on Sunday but i am taking archive log file daily evening.
Wednesday my database crash that means i lost all control file,redo log file,datafile etc.
I have archived log file backup till Tuesday Night and other files like control file,datafile etc of Sunday .
1)Is it possible to recover database till tuesday if yes HOW to use archive log file.
(See SCN no of control file and datafiles is same ,if we use RECOVER DATABASE command oracle shows that media recovery is not requide.)
we don't have current control file we had lost in media crash.
null

Dear friend
In this scenario
you lost the contorl file
1>If you have old copy of Contorl file,
which has the current structure of the
database and all the archive files then
you can recover the database with
Ponint in time recovery (Using Backup Controlfile)
suresh

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.

Removing Redo Log Files? What's Normal?

Hello,
I'm new to Oracle and I've been using Informix for years. We currently have Oracle 9.2 running on Windows 2000 Server machine and apparently the redo log files keep filling up the disk drives they reside on. This is happening about every two weeks since we go out and delete the files when we remember.
My question is does Oracle have a "normal" way of removing old redo logs automatically rather than having to remove them manually? In the Informix world I can set the logical logs so that they write over previously used logs once they are no longer used. Is there a similar way to configure Oracle?
Thanks for helping out.
Gregg Walker

Do not delete your old log files: you need them.
That's how Oracle does recovery when you lose a datafile or a drive. You copy over the missing stuff from your back-up and then Oracle re-applies the chnages from the REDO logs thereby bringing your database back up to date. No work lost. Result!
Of course, if you don't take up a backup then holding on to REDO logs is pointless. In which case, set the database to run in NOARCHIVELOG mode.
However, I strongly advise you to run in ARCHIVELOG mode. You may find this part of the administrator's guide informative: http://download-west.oracle.com/docs/cd/B10501_01/server.920/a96521/archredo.htm#4553
Cheers, APC

Where RFS exactly write redo data ? ( archived redo log or standby redo log ) ?

Good Morning to all ;
I am getting bit confused from oracle official link . REF_LINK : Log Apply Services
Redo data transmitted from the primary database is received by the RFS on the standby system ,
where the RFS process writes the redo data to either archived redo log files or standby redo log files.
In standby site , does rfs write redo data in any one file or both ?
Thanks in advance ..

Hi GTS,
GTS (DBA) wrote:
Primary & standby log file size should be same - this is okay.
1) what are trying to disclose about largest & smallest here ? - You are confusing.
Read: http://docs.oracle.com/cd/E11882_01/server.112/e25608/log_transport.htm#SBYDB4752
"Each standby redo log file must be at least as large as the largest redo log file in the redo log of the redo source database. For administrative ease, Oracle recommends that all redo log files in the redo log at the redo source database and the standby redo log at a redo transport destination be of the same size."
GTS (DBA) wrote:
2) what abt group members ? should be same as primary or need to add some members additionally. ?
Data Guard best practice for performance, is to create one member per each group in standby DB. on standby DB, one member per group is reasonable enough. why? to avoid write penalty; writing to more than one log files at the standby DB.
SCENARIO 1: if in your source primary DB you have 2 log member per group, in standby DB you can have 1 member per group, additionally create an extra group.
primary
standby
Member per group
2
1
Number of log group
4
5
SCENARIO 2: you can also have this scenario 2 but i will not encourage it
primary
standby
Member per group
2
2
Number of log group
4
5
GTS (DBA) wrote:
All standby redo logs of the correct size have not yet been archived.
- at this situation , can we force on standby site ? any possibilities ?
you can not force it , just size your standby redo files correctly and make sure you don not have network failure that will cause redo gap.
hope there is clarity now
Tobi

What is the purpose of standby redo log files

Hi,
What is the purpose of the standby redo log files in DR?
what if the standby redo log files are created? or else not created?
Please explain
Thanks

3.1.3 Configure a Standby Redo LogA standby redo log is required for the maximum protection and maximum availability modes and the LGWR ASYNC transport mode is recommended for all databases. Data Guard can recover and apply more redo data from a standby redo log than from archived redo log files alone.
You should plan the standby redo log configuration and create all required log groups and group members when you create the standby database. For increased availability, consider multiplexing the standby redo log files, similar to the way that online redo log files are multiplexed.>
Reference http://download.oracle.com/docs/cd/B19306_01/server.102/b14239/create_ps.htm#i1225703
HTH
Anand

Use of standby redo log files in primary database

Hi All,
What is the exact use of setting up standby redo log files in the primary database on a data guard setup?
any good documents?

A standby redo log is required for the maximum protection and maximum availability modes and the LGWR ASYNC transport mode is recommended for all databases. Data Guard can recover and apply more redo data from a standby redo log than from archived redo log files alone.
You should plan the standby redo log configuration and create all required log groups and group members when you create the standby database. For increased availability, consider multiplexing the standby redo log files, similar to the way that online redo log files are multiplexed.
refer the link,and Perform the following steps to configure the standby redo log.:-
http://download.oracle.com/docs/cd/B19306_01/server.102/b14239/create_ps.htm#i1225703
If the real-time apply feature is enabled, log apply services can apply redo data as it is received, without waiting for the current standby redo log file to be archived. This results in faster switchover and failover times because the standby redo log files have been applied already to the standby database by the time the failover or switchover begins.
refer the link
http://download.oracle.com/docs/cd/B19306_01/server.102/b14239/log_apply.htm#i1023371

Oracle 10g R2 Database Redo Log Files

I had 3 redo log files, each of size 50 MB. i added 3 more redo log files, each of size 250 MB.
Database is running in archive mode, files are generating with different sizes like 44 MB and 240 MB, i need to know is this harm for database or not?
to make all archive redo log files generation of equal size what should i do?
Please guide

Waheed,
When the redo log switch willbe happening,oracle would be asking archiver to log that into the archive file.So in case you have any parameters set to make the switch happen at certain time,depending on the activity of teh database,the archive file size may vary.There is no harm wit the different sizes of the files.What matters is the transaction informaiton contained in them not their size.
to make all archive redo log files generation of equal size what should i do?
As mentioned by Syed, you can make the switch happen at a defined interval which will not ensure but still will be a step to make the archive files of the same size.But I shall say you should bother more about making sure that the files are available rather than their size.
Aman....

Backup vs redo log files

Hi,
Can anyone tell me what's the real difference between a backup file and a redo log file/archived redo log file and the scenarios (examples) when each of them can be used (for example, "......") ? Both are used for database/instance recovery. I have read the concepts of there 2 terms, but I need some additional information about the difference.
Thanks!

Roger25 wrote:
What i still don't understand is how redo mechanism works; I know, redo logs records changes made to the database and it's used to re-do informations in case of a system failure/crash, for example. Ok, let's say I have a huge update, but when the system crash has occured, the transaction is neither comitted, nor rolled back. Then, how this redo is useful? If a system crash occur, all those updates aren't rolled back automatically? So the database state is as before executing that huge update? So in this case, 'what to redo'?No, with the system's crash, the transaction never gets a chance to get committed (and even rolled back) because a commit is only supposed to happen if there is an explicit or implicit commit statement is issued. Now, for the redo , with the statement, a commit marker is entered at the end of the redo stream of that transaction denoting that it's finally over now and for the corresponding transaction, the status is cleared from the transaction table that's stored in the Undo segment in which the Undo information of that transaction is stored. If you have given a huge update, the redo would be very highly required as you should be knowing that it's not all the time that the dirty buffers that are written to the data files unlikely the redo log files which are written every 3 econds. This means, there is a very fair chance that many changes have yet not even propagated to the data files for which the change vectors are now already there in the redo log files. Now, for the sake of clarity, assume that this transaction was actually committed! So now, without those changes be applied to the data files how Oracle can actually show the committed reults when the database next time would be opened? For this purpose, the redo change vectors are required. And for the uncommitted transactions , the applcation of the redo change vectors would keep on updating the Checkpoint numbers of the data files and would eventually get them synched with the control file and redo log files, without which the database would never be opened.
HTH
Aman....

The file structure online redo log, archived redo log and standby redo log

I have read some Oracle documentation for file structure and settings in Data Guard environment. But I still have some doubts. What is the best file structure or settings in Oracle 10.2.0.4 on UNIX for a data guard environment with 4 primary databases and 4 physical standby databases. Based on Oracle documents, there are 3 redo logs. They are: online redo logs, archived redo logs and standby redo logs. The basic settings are:
1. Online redo logs --- This redo log must be on Primary database and logical standby database. But it is not necessary to be on physical standby database because physical standby is not open. It doesn't generate redo log. However, if don't set up online redo log on physical standby, when primary failover and switch standby as primary. How can standby perform without online redo logs? In my standby databases, online redo logs have been set up.
2. Archived redo logs --- It is obviously that primary database, logical and physical standby database all need to have this log file being set up. Primary use it to archive log files and ship to standby. Standby use it to receive data from archived log and apply to database.
3. Standby redo logs --- In the document, it says A standby redo log is similar to an online redo log, except that a standby redo log is used to store redo data received from another database. A standby redo log is required if you want to implement: The maximum protection and maximum availability levels of data protection and Real-time apply as well as Cascaded destinations. So it seems that this standby redo log only should be set up on standby database, not on primary database. Am my understanding correct? Because I review current redo log settings on my environment, I have found that Standby redo log directory and files have been set up on both primary and standby databases. I would like to get more information and education from experts. What is the best setting or structure on primary and standby database?

FZheng:
Thanks for your input. It is clear that we need 3 type of redo logs on both databases. You answer my question.
But I have another one. In oracle ducument, it says If you have configured a standby redo log on one or more standby databases in the configuration, ensure the size of the current standby redo log file on each standby database exactly matches the size of the current online redo log file on the primary database. It says: At log switch time, if there are no available standby redo log files that match the size of the new current online redo log file on the primary database. The primary database will shut down
My current one data gurard envirnment setting is: On primary DB, online redo log group size is 512M and standby redo log group size is 500M. On the standby DB, online redo log group size is 500M and standby redo log group size is 750M.
This was setup by someone I don't know. Is this setting OK? or I should change Standby Redo Log on standby DB to 512M to exactly meatch with redo log size on primary?
Edited by: 853153 on Jun 22, 2011 9:42 AM

Delete old and backed up archive log,

Hi all,
Am trying to modify our RMAN backup script to delete old and backed up archive logs off the disk.
We run daily Incremental L0 or L1 backups, with 3 daily archive log backups. Currently we delete archive logs as they are backed up (backup archivelog all delete input). However, we are considering leaving x days worth of archive logs on disk, just in case, quick restore is needed (e.g. tablespace media recovery etc. etc.)
For example,
We can delete archive logs old tha n x (where x=no_days depending on database) by,
delete archivelog until time 'sysdate-15';
We can also delete archive logs that have been backed up to disk by,
delete archivelog all backed up 1 times to disk;
Questions,
1) Why does 'backed up 1 times to disk' require the 'all' in the statement ?
2) Is there any way to combine the 2 statements ? (backed up 1 times and older than x days ?). Just being a bit extra cautious to ensure that we have everything backed up. In real-world shouldn't be a problem, as we will be alerted to any backup failures, but trying to cater for the very worst situation.
Thanks for your help and insight.

Hi,
Scratch the questions. Found the answer in another thread. Seems when I tried to combine the statements initally, I had a typo.
It is now working as expected.
Thanks and regards,

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

How to recover from corrupt redo log file in non-archived 10g db

Hello Friends,
I don't know much about recovering databases. I have a 10.2.0.2 database with corrupt redo file and I am getting following error on startup. (db is non archived and no backup) Thanks very much for any help.
Database mounted.
ORA-00368: checksum error in redo log block
ORA-00353: log corruption near block 6464 change 9979452011066 time 06/27/2009
15:46:47
ORA-00312: online log 1 thread 1: '/dbfiles/data_files/log3.dbf'
====
SQL> select Group#,members,status from v$log;
GROUP# MEMBERS STATUS
1 1 CURRENT
3 1 UNUSED
2 1 INACTIVE
==
I have tried this so far but no luck
I have tried following commands but no help.
SQL> ALTER DATABASE CLEAR UNARCHIVED LOGFILE GROUP 3;
Database altered.
SQL> alter database open resetlogs;
alter database open resetlogs
ERROR at line 1:
ORA-01139: RESETLOGS option only valid after an incomplete database recovery
SQL> alter database open;
alter database open
ERROR at line 1:
ORA-00368: checksum error in redo log block
ORA-00353: log corruption near block 6464 change 9979452011066 time 06/27/2009
15:46:47
ORA-00312: online log 1 thread 1: '/dbfiles/data_files/log3.dbf'

user652965 wrote:
Thanks very much for your help guys. I appreciate it. unfortunately none of these commands worked for me. I kept getting error on clearing logs that redo log is needed to perform recovery so it can't be cleared. So I ended up restoring from earlier snapshot of my db volume. Database is now open.
Thanks again for your input.And now, as a follow-up, at a minimum you should make sure that all redo log groups have at least 3 members. Then, if you lose a single redo log file, all you have to do is shutdown the db and copy one of the good members (of the same group as the lost member) over the lost member.
And as an additional follow-up, if you value your data you will run in archivelog mode and take regular backups of the database and archivelogs. If you fail to do this you are saying that your data is not worth saving.

Delete old and unused Archived Redo Log Files

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