How to setup oracle database to archivelog mode and auto delete ?

Question

Oracle 11g R2
- How to setup database to archive log mode and have oracle only save 24 hours of archive logs
and delete the rest. So at any given time I will have only 24 hours of archive log and not more.
So only 1 day of archive logs.
- Let me know the database parameters I need to setup to accomplish this.
- I don't want to use the RMAN
- I am not setting up the database to archive log mode for recovery purpose. I am setting up archive log mode
so we can use the log miner tool to dig up achives to see log activity for any performance & tuning.
Edited by: johnpau2013 on May 9, 2012 6:09 PM

Answer 1

johnpau2013 wrote:
Thanks everyone for there responses.
I need to rephrase and explain everyone as what I wanted to do exactly. This might help everyone understand and suggest me.
We have oracle database 11g r2. Its a test database. Nothing is critical. We use EXPDP utility to backup the entire database every night. Which is enough for us to recover incase something happens. Even if we loose some data. That's fine.
We are testing our web application on this oracle test database for performance & tuning.
One thing we have noticed is that the redo logs are switching very frequently. 50MB each log file and there are 5 logs. each log switches every 40 seconds. So we wanted to see what is getting written in this redo logs. We wanted to use the LOG MINER tool in OEM to read the logs. It needed our database to be setup in archive log mode. So the log miner can read the archive logs and show us the sql's within the archive logs.
Now when we setup the archive log mode on our database. By default the archive logs destination was set to flash recovery area ( may be oracle default archive log location is flash recovery area folder).
We have setup the db_recovery_file_dest_size to 100GB. Now within 2 days we have filled up the flash recovery area folder. Database was frozen. Then we realized that its because oracle couldn't write archive logs. Because it reached the 100GB. Then we physically deleted files in the flash recovery area folder. Thinking it would help us start the frozen oracle database. But it didn't . The we realized that we are doing something wrong. As Oracle does not know that at OS level we deleted the files. Then temporarily we changed the db_recovery_file_dest_size to 130GB and were able to start the oracle database. Later we turned OFF the archive log mode.
Being a rookie DBA we would have not read something properly.
Finally:
We wanted to know how to always keep only 1 day of archive logs (only for our performance tuning ) and not more than that. All we need this 1 day of archive logs is to use the log miner to read them. Backup is NOT our priority here. Only be able to read the archive logs from LOG MINER is PRIORITY.
Correct me if I am wrong.Okay, so its making much more sense now, thanks for explaining your requirement.
Database won't honor anything that you would do over the o/s without telling it. Your deletion of the archive log from the o/s location is NOT updated in the control file of the database and that's why, even when you had deleted the entire 100GB , from the db perspective, the space was still marked as used. This is the same which would happen even if you would increase the space from 100gb to whatever size as well. To delete the space, you would need to update the database's control file and that you can do from RMAN using its two commands , crosscheck backup following with deleted expired backup . The first command would find that which database backup files are NOT on the o/s which are shown in the control file and would mark all of them as expired. The second command would simply delete those expired files. This would update the control file and you would have your 100gb or whatever space, given back to you.
To keep the archive logs of just one day, set up that Retention Policy for RMAN to either number of copies using the Redundancy option(default and set to 1) or Recovery Window. I believe for you Redundancy would be a suitable choice but you can have a read and play around with it. Setting it up would mark the files as Obsoleted and finally, you can write a small RMAN script to delete those obsoleted files.
Now, what I don't understand is that why you want to keep on generating the archive logs just for the log miner? If you would have generated them once and figure out the reason for extensive redo generation(did you try increasing the redo log file size, 50mb seems to be smallish) , I don't think that there is any reason to keep on generating the archive logs still .
And last part, for your question asked about that whether we can use RMAN to put the db in the archive log and is it a backup tool, yes and yes.
HTH
Aman....