Ramin Hossaini (blog)

Turning Archive-log mode on and off

You can check what mode the database is in with:

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SELECT LOG_MODE FROM SYS.V$DATABASE;

If you do not specify an archive-log location, it will end up going to a directory like $ORACLE_HOME/dbs - which can be quite a mess.
Check where it's going:

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SHOW PARAMETER log_archive_dest;

It would be good practice to set the location if it doesn’t show one.
To turn archive-log-mode on or off:

shutdown database:

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SHUTDOWN IMMEDIATE
STARTUP RESTRICT
SHUTDOWN

Mount the database:

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ALTER DATABASE MOUNT;

Then issue one of the following:

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ALTER DATABASE NOARCHIVELOG;
ALTER DATABASE ARCHIVELOG;

If the location hasn’t been set yet:

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ALTER SYSTEM SET LOG_ARCHIVE_DEST = "/ARC_LOCATION";

Then open the database:

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ALTER DATABASE OPEN;

There might also be archivelog related entries in your PFILE, which you should also make changes to.

Related posts:

1. Backing up an Oracle database without RMAN
2. Oracle: Recycle listener.log
3. Oracle: Recovering a Tablespace
4. Cancel Oracle shutdown
5. Enabling Trace