It is always a best practice and an Oracle recommended practice to have archive log mode enable, which facilitates many benifits:
- The database can be completely recovered from both instance and media failure till the last committed transaction
- The user can perform online backups, i.e., back up tablespaces while the database is open and available for use (hotbackup).
- Archived redo logs can be transmitted and applied to the standby database
- Oracle supports multiplexed archive logs to avoid any possible single point of failure on the archive logs.
- The user has more recovery options, such as the ability to perform tablespace-point-in-time recovery (TSPITR)
When to disable Archive Mode?
I am trying to ask in which scenarios to disable Archive Mode?
There are instance say for example the flash recovery area (or Hard disk per sa) is full and you have to immediately release some space until a new space is added on to the server.
But that is one nasty example I could come across, but in most cases you will have the archive log mode enabled. Please also check:
The answer stands based on the environment and the requirement of a particular scenario or circumstances, and I cant readily recall any other instances. But we will be able to further assist you if you elaborate what is your exact requirement to find out answer to this question.
As noted, archivelog mode should not be disabled during normal operations. The only time it can be disabled is during database upgrades or Apps upgrades. Disabling archivelog mode will speed up the upgrades. Archivelog mode can be disabled because if there is a major unrecoverable issue with the database/app upgrade, it is recommended to restore from backups and restart the upgrade
Disabling Archivelog mode should never be done for your production instance -- http://www.oracle.com/pls/db102/search?remark=quick_search&word=Archivelog&tab_id=&format=ranked
Even though Oracle recommends disabling archivelog during the upgrade, please note that if Oracle streams is used you can't disable it.
Complete Checklist for Manual Upgrades to 11gR1 (Doc ID 429825.1)
If the database is running in ARCHIVELOG mode the preupgraded database can be recovered up until the database was started with the UPGRADE option -- Oracle 11gR2 Upgrade Companion (Doc ID 785351.1)
Personally, I haven't noticed that big impact on the upgrade downtime when archivelog is disabled, and I would say you should try the upgrade with archivelog enabled/disabled and see if it makes a difference for you.
For your development instances, it should be OK to disable atchivelog mode as it would be easier to re-clone the instance than recovering it from backup.
I am disabling archiving for when we perform DR next weekend.
Restore the LIVE instance copy to the DR server.
Run cloning scripts to reconfigure the cloned database instance.
Disable archiving for the duration of DR (the instance will be retired the following week anyway)
Run cloning scripts to reconfigure the cloned application
The reason we disable archiving here is because it is not need for the weekend - any changes we make to the DR copy dont need to be saved. We also dont have the space to save the archive logs if generated on that DR server.
As others have mentioned here, we also disable archiving during heavy duty patching. We might also turn it off it there is going to be a specifically deep process that will run and generate silly amounts of redo that for some reason or other we have deemed not worthy of keeping.