archived redo log files

Posted on 2006-11-20
Last Modified: 2010-07-27
Dear Oracle gurus
              I am facing a problem.we have configured our database in archieve log mode.And data comes in bulk. so size of archieved redo log increased in a huge ammount. So please suggest me how to manage big archive redo log files. Do there is any way to create multiple small size archived redolog file despite having a big archieved redo log file. And what are standarad ways to manage big archieved redo log files?

Naveen Mathur
Question by:hg1010
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Expert Comment

ID: 17978975
   Yes, you can create more number of online redo log groups with smaller size, if you want to have small size archive redo logs.
Other options are, you can do your data load with NOLOGGING clause and take a full backup of the database once your work is done. This will reduce the number of archive logs during the data load. Another way is to switch off archiving during the dataload and enable back after your dataload is finished. With either of the options, you will need to take a full database backup after dataload and the database is not recoverable to point-in-time, as the operations are not logged.
Also, you can use insert /*+ append */ hint to reduce number of redo logs.
LVL 48

Accepted Solution

schwertner earned 500 total points
ID: 17979068
If you have configured your server in Archived log you have to support this mode.
It is not good idea to decrease the size of the archive log - this can lead to problems
with the ARCHn proceses - they will not do the job timely and the server will have to wait.

If the problem is how to keep this amount of logs there is another solution.
You can initiate a new incarnation - making a new cold backup, reset the log files and
begin to store the newly created archived logs.
LVL 35

Expert Comment

by:Mark Geerlings
ID: 17979243
Can Oracle create multiple, small size archived redolog files despite having big on-line redo log files?
No.  The size of the archived redo log files is determined by the size of the on-line redo log files.

What kind of opplication do you have?  Is it an OLTP system, or a data warehouse?  Are you sure that you need large on-line redo log files?

You don't need to keep archived redo log files older than your latest backup.  What type of backup do you use, RMAN or user-controlled?  How frequently do you do a full backup?
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LVL 48

Expert Comment

ID: 17980076
The archived log files are copies of the online redo log files.
The problem is not if they are small or big.
The problem mainly arises when the DBA has too many archived logs on the
box and the disk space is not enough.
The archived logs should be transfered to other machine as soon as possible
not only for the disk space but mainly for ecurity reason

Expert Comment

ID: 17981662
you just need to create new redolog groups with small size?

But these will affect the performance of system. Do you like that?

Alter natively just write a script to mount a remote drive on system and transfer your files.

Do you use nas server or storge ?

Please ask if you have some other query

Haider Ali Syed
LVL 11

Expert Comment

ID: 18005322
I agree with other experts that reducing the redo log files will effect performance.

Most effective method i can think of is:

- Create a script
- Schedule frequent backup of the database. Either cold/hot or RMAN backups.
- Use OS commands to delete archive log files created before the backup. (delete files based on date and timestamp) using a simple remove command
$ rm

This way you will only have archived files/data between backups. Use of RMAN will be most effect in your case as it allows to backup database in FULL OR you can just backup ARCHIVED FILES for a days (For example: 20 archive files in 1 backup piece in a backup set).


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