archive processes appearing in ALERT log

[a128]

I notice when a DB starts up, there is only one ARC0 process recorded in the ALERT log. However, after a while, I see the following lines:

---------------
ARC0: Beginning to archive log# 1 seq# 2404
Tue Dec 10 11:49:53 2002
Thread 1 advanced to log sequence 2405
Tue Dec 10 11:49:53 2002
Current log# 2 seq# 2405 mem# 0: C:\ORACLE\ORADATA\SILICON1\REDO2A.LOG
Current log# 2 seq# 2405 mem# 1: C:\ORACLE\ORADATA\SILICON1\REDO2B.LOG
Tue Dec 10 11:49:53 2002
ARC0: Completed archiving log# 1 seq# 2404
ARC0: STARTING ARCH PROCESSES
ARC1 started with pid=16
Tue Dec 10 11:49:53 2002
ARC0: STARTING ARCH PROCESSES COMPLETE
Tue Dec 10 11:49:54 2002
ARC1: Archival started
Tue Dec 10 14:35:39 2002
Thread 1 advanced to log sequence 2406
Current log# 3 seq# 2406 mem# 0: C:\ORACLE\ORADATA\SILICON1\REDO3A.LOG
Current log# 3 seq# 2406 mem# 1: C:\ORACLE\ORADATA\SILICON1\REDO3B.LOG
Tue Dec 10 14:35:39 2002
ARC1: Beginning to archive log# 2 seq# 2405
ARC1: Completed archiving log# 2 seq# 2405
-----------------

So it appears another archive process called "ARC1" has been started. Is it because it's too busy to catch up thus another archive process is started? The log does not appear it could not catch up.

Thanks,

[stecal]

There is currently no way to keep the number of archive processes to a specific number of processes. This is documented in [BUG:1921532] which is fixed in 8.1.7.3 and 9.0.1. This fix introduces EVENT 16155 which when set to level 1 prevents LOG_ARCHIVE_MAX_PROCESSES from being exceeded in Oracle8i.

event="16155 trace name context forever, level 1"

In Oracle9i the behaviour is already such that LOG_ARCHIVE_MAX_PROCESSES will not be exceeded so there is no controling event.

The initialization parameter LOG_ARCHIVE_MAX_PROCESSES specifies the number of ARCH processes to be invoked, when LOG_ARCHIVE_START is set to TRUE. When LOG_ARCHIVE_MAX_PROCESSES is set to the default value of 1, the system determines how many ARCn processes are needed and LGWR automatically starts up more ARCn processes when the database workload requires more. In 8i it is not possible to stop further archiver processes from being started. But with the above solution, you can control the processes for the archiver and the parameter does not allow automatic spawning of ARCn processes.