Oracle Redo logs processes

[Sanjay Verma]

Hi Friends,
I've noticed that my system has redo log processes running as below:

$: ps -ef | grep -i rc
oracle 27956 1 0 Jun 1 ? 5:01 ora_arc0_DB1
oracle 4688 1 0 Jul 10 ? 0:00 ora_arc1_DB1

As I understand, the processes are spawned automatically but in this case, I can see that the active time for the second process is "0.00" always. Is that a runaway process or normal to the system?

[Steven E. Protter · Accepted solution]

These are archive log proceses.

If you have the database in archive log mode, there should be some activity.

If archive log mode is on and they are being created, there is nothing to worry about. If you let the database run long enough, you'll eventually get some cpu time.

I suspect the database is not in archive log mode.

Lets check it.

su - oracle # the user that owns the database binaries.

sqlplus internal
select * from v$database;

It indicates the mode the database is in.

SEP

[malay boy]

Hi,

This is not redolog process but achiver process.

I guest you set the log_archive_max_process=2 in oracle init.ora file.

It means that oracle will start two archiver upon instance start even though you only need one(due to low activity).

And this is not a running process.

regards
mB

[malay boy]

Hi,

This is not redolog process but achiver process.

I guest you set the log_archive_max_process=2 in oracle init.ora file.

It means that oracle will start two archiver upon instance start even though you only need one(due to low activity).

And this is not a running process.

regards
mB

[malay boy]

Hi,

This is not redolog process but achiver process.

I guest you set the log_archive_max_process=2 in oracle init.ora file.

It means that oracle will start two archiver upon instance start even though you only need one(due to low activity).

And this is not a running process.

regards
mB

[malay boy]

Hi,

This is not redolog process but achiver process.

I guest you set the log_archive_max_process=2 in oracle init.ora file.

It means that oracle will start two archiver upon instance start even though you only need one(due to low activity).

And this is not a running process.

regards
mB

[malay boy]

Hi,

This is not redolog process but achiver process.

I guest you set the log_archive_max_process=2 in oracle init.ora file.

It means that oracle will start two archiver upon instance start even though you only need one(due to low activity).

And this is not a running process.

regards
mB

[malay boy]

Hi,

This is not redolog process but achiver process.

I guest you set the log_archive_max_process=2 in oracle init.ora file.

It means that oracle will start two archiver upon instance start even though you only need one(due to low activity).

And this is not a running process.

regards
mB

[malay boy]

Hi,

This is not redolog process but achiver process.

I guest you set the log_archive_max_process=2 in oracle init.ora file.

It means that oracle will start two archiver upon instance start even though you only need one(due to low activity).

And this is not a running process.

regards
mB

[malay boy]

Hi,

This is not redolog process but achiver process.

I guest you set the log_archive_max_process=2 in oracle init.ora file.

It means that oracle will start two archiver upon instance start even though you only need one(due to low activity).

And this is not a running process.

regards
mB

[malay boy]

Hi,

This is not redolog process but achiver process.

I guest you set the log_archive_max_process=2 in oracle init.ora file.

It means that oracle will start two archiver upon instance start even though you only need one(due to low activity).

And this is not a running process.

regards
mB

[malay boy]

Hi,

This is not redolog process but achiver process.

I guest you set the log_archive_max_process=2 in oracle init.ora file.

It means that oracle will start two archiver upon instance start even though you only need one(due to low activity).

And this is not a running process.

regards
mB

[malay boy]

wow!!! so many reply from me.Sorry guy's my IE browser just back from lunch.That's why a bit wacko.

regards
mB

[Sanjay Verma]

Hi Steven/Malay,
As you can see, it's "0:00" since Jul10. Is that of any concern?

[T G Manikandan]

you have specified multiple archiver processes which should be helpful for archiving to multiple destinations.

For example if you are archiving the files to multiple destinations then the single process cannot take that load or it should do the task simultaneously.

[twang]

Since Oracle 8i supports multiple archive destinations it also supports multiple archiver processes to ease the load on a single archiver.
LOG_ARCHIVE_MAX_PROCESSES specifies the number of ARCH processes to be invoked.
This value is evaluated at instance startup if the LOG_ARCHIVE_START initialization parameter has the value TRUE. If the LOG_ARCHIVE_START is true and LOG_ARCHIVE_MAX_PROCESSES is not set explicitly it will start the arc0 process. Otherwise if LOG_ARCHIVE_MAX_PROCESSES is explicitly set to a value (range 1-10) then it will start additional archiver processes named arc0, arc1, arc2 . . . . . etc. There is no need to change this parameter from its default value of 1, because the system determines how many ARCn processes are needed and LGWR automatically starts up more ARCn processes when the database workload requires more.

If LOG_ARCHIVE_START is set to true, Oracle starts up a single archiver
process names ARC0. Subsequently if the parameter is changed using the ALTER
SYSTEM command it will start the specified number of archive processes. For
example:
SVRMGRL>alter system set LOG_ARCHIVE_MAX_PROCESSES=4;
will invoke additional processes ARC1 , ARC2 and ARC3, I guess the ora_arc1_DB1 is started then.

[malay boy]

Hi,
If it was me.I would'nt worry to much.But may I know what is your LOG_ARCHIVE_MAX_PROCESSES parameter in init.ora file or you can run below sql :

select name,value from v$parameter where name like '%log%archive%max%'

select * from v$database;

regards
mB

[T G Manikandan]

This should not worry you!

Also,this is done by the LGWR
which automatically spawns processes for more load.

This happens also when the log switches are happening at a faster rate.

The parameter setting LOG_ARCHIVE_MAX_PROCESSES in init.ora file is the initial amount of processes to be started.

[Alexander M. Ermes]

Hi there.
I think, there is a parameter in the init.ora
activated called 'LOG_ARCHIVE_MAX_PROCESSES'.

You can check it with the query on v$archive_processes. It should show the arc1 as idle.

These multiple archive processes come in handy, if you have several redo logs to archive. If the change goes fast, one process can handle the first log and so on.
This helps with your performance.
If you have the Oracle online documnetation, look for this :

file:///disk/doc/server.817/a76956/archredo.htm#12156

If you need more info, let us know.
Rgds
Alexander M. Ermes

[malay boy]

Alex,
Yap you are the guru.here are the result from our development database :

SQL> select * from v$archive_processes;

PROCESS STATUS LOG_SEQUENCE STAT
---------- ---------- ------------ ----
0 STOPPED 0 IDLE
1 STOPPED 0 IDLE
2 STOPPED 0 IDLE
3 STOPPED 0 IDLE
4 STOPPED 0 IDLE
5 STOPPED 0 IDLE
6 STOPPED 0 IDLE
7 STOPPED 0 IDLE
8 STOPPED 0 IDLE
9 STOPPED 0 IDLE

10 rows selected.

I guest in your case you will see 2 process with status running and stat for one of them are idle.

In my case,all the arc process are not running that's why it showed all stopped.

regards
mB

[Sanjay Verma]

Alex - Thanks very much. The docs (will refer) but the table info is really helpful.
TG - Thanks for the parameter.
Malay - Thanks for the table info.
Twang - Appreciate your comprehensive info.
Steven - Thanks for the table info.

Appreciate again.

[Yogeeraj_1]

hi,

to add to the above replies, note that
to know how many archiving proccess running you can run the following query:

select program from v$process where program like '%(ARC_)%'

and also note that there exists a side effect of having more than one archiver.

If automatic archiving is turned on then all of the archiver process will try to archive this logfile, however they will not be able to aquire the lock 'kcrrlt', the lock to protect multiple arch processes from archiving the same logfile.

The failing process process will write to the trace/alert message that it was unable to archive the logfile.

The file is successfully archived by some other process.

hope this helps too!
regards
Yogeeraj

[Sanjay Verma]

Hi Yogeeraj,
Thanks for the good information. Yes, I've made of note of this.
Cheers, Sanjay

[twang]

A little opinion add to above, multiple archive processes can be beneficial if you have more than one archive log destination specified. Archive processes are added automatically to balance your workload.
However, if you feel your load is such that more processes are needed before Oracle decides to add them you can use the LOG_ARCHIVE_MAX_PROCESSES parameter to increase the initial number of ARC processes.
Good luck!
twang