ARC0: Media recovery disabled

I have seen a lot of error messages in alert.log.
ARC0: Media recovery disabled
ARC1: Media recovery disabled

When I grep the arc processes, those processes still alive in the background.
[oracle92@aysbdbs06 bdump]$ ps -ef | grep arc |  grep LHCCPOC
oracle92  5593     1  0 Dec10 ?        00:00:01 ora_arc0_LHCCPOC
oracle92  5595     1  0 Dec10 ?        00:00:00 ora_arc1_LHCCPOC

Refer to this Oracle document, ARC0: Media Recovery Disabled (Doc ID 131119.1).
The root cause is an archive process has been started on a database which is running in NOARCHIVELOG mode. 

In my environment, I have found this parameter LOG_ARCHIVE_START is TRUE.
Even the database is in NOARCHIVELOG mode, but the archival processes will still running 
if the parameter above is TRUE.






LOG_ARCHIVE_START initialization parameters is deprecated in Release 10.1.

The key to the fix is if your intend your database to be running in ARCHIVELOG or 
NOARCHIVELOG mode. 

RESOLUTION



1.If intention is to have database in ARCHIVELOG mode: 1.1. Alter the database log mode: SQL> startup mount; SQL> alter database archivelog;

2. If intention is to have database in NOARCHIVELOG mode: 2.1. Do not start an archive process on startup: set LOG_ARCHIVE_START=FALSE (default) 2.2. Ignore message in alert.log