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Archivelog and the purpose

Fauziah Mahdan
Super Advisor

Archivelog and the purpose

Hi all,
Allow me ask this simple question.
What is archivelog for in oracle Data Guard?
Can we all delete this file? What is the impact? If db crash can it be restored?
Is it normal it will create 3GB archivelog daily?

Honored Contributor

Re: Archivelog and the purpose

The archivelogs are a way to get online backups.

When Oracle is configured for online backups, it will produce an archivelog of all database changes.

To completely recover a database, you'll need the latest full dump of the database *and* an unbroken series of archivelogs from the time of the last dump up to the present. This way you can return the database to the exact state it was just before the problem that caused the need to recover.

If you take a full dump of the database and are sure you don't need to restore the database to a point in time before the dump, you're then free to delete all the archivelogs from the time before the dump.

3GB of archivelog daily means that you get about 3GB worth of changes to your database. Of course the archivelog is a bit bigger than the actual sum of changes, because it includes change timestamps and some other metadata.

Honored Contributor

Re: Archivelog and the purpose


As Matti mentions above, your database is generating archiving log files with respect to the amount of transaction occurring on it.

In a standby database condition, these archived log files are copied from the Primary database to the Standby database where they are applied. The log files make the Standby database more current of the primary database.

In cases of major crashes, you may be required to provide some of the archived log files during the recovery process. Of course, the full backup + archived log files relative to last full backup.

If you have RMAN configured, "management" of these archived redologs are much easier. All you have to do is scheduled RMAN backup of archived redologs at different point in time during day. The backup process can be configured to automatically delete the archived redolog files that have already been backed up.

if you need further clarification, please let us know.

kind regards
No person was ever honoured for what he received. Honour has been the reward for what he gave (clavin coolidge)