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archive redo log too small

Hello,

On one ECC6.04 system with Oracle 11.2.0.2, we regularly have checkpoint is not complete.

Before re-increasing size or the number of redo groups again, I have check their sizes:

ls -altrh /oracle/PRD/oraarch

total 4269436

-rw-r--r--   1 oraprd   dba            0 Jun 15  2011 .ch.unige.nsr.ignore

--w-------   1 root     root        500M Jun 21  2011 2_DELETE_ME_ON_ARCHIVER_STUCK

--w-------   1 root     root        500M Jun 21  2011 1_DELETE_ME_ON_ARCHIVER_STUCK

-rw-r--r--   1 root     root         791 Jun 21  2011 0_DELETE_ME_ON_ARCHIVER_STUCK.README

-rw-r-----   1 oraprd   dba          28M Apr  3 22:31 PRDarch1_10262_761304167.dbf

-rw-r-----   1 oraprd   dba          35M Apr  3 23:27 PRDarch1_10263_761304167.dbf

-rw-r-----   1 oraprd   dba          40M Apr  3 23:27 PRDarch1_10264_761304167.dbf

-rw-r-----   1 oraprd   dba          40M Apr  3 23:27 PRDarch1_10265_761304167.dbf

-rw-r-----   1 oraprd   dba          35M Apr  3 23:27 PRDarch1_10266_761304167.dbf

-rw-r-----   1 oraprd   dba          30M Apr  3 23:27 PRDarch1_10267_761304167.dbf

-rw-r-----   1 oraprd   dba          33M Apr  3 23:27 PRDarch1_10268_761304167.dbf

-rw-r-----   1 oraprd   dba          29M Apr  3 23:28 PRDarch1_10269_761304167.dbf

-rw-r-----   1 oraprd   dba          31M Apr  3 23:28 PRDarch1_10270_761304167.dbf

-rw-r-----   1 oraprd   dba          29M Apr  3 23:28 PRDarch1_10271_761304167.dbf

-rw-r-----   1 oraprd   dba          34M Apr  3 23:28 PRDarch1_10272_761304167.dbf

-rw-r-----   1 oraprd   dba          40M Apr  4 00:13 PRDarch1_10273_761304167.dbf

-rw-r-----   1 oraprd   dba          30M Apr  4 00:30 PRDarch1_10274_761304167.dbf

-rw-r-----   1 oraprd   dba          32M Apr  4 00:30 PRDarch1_10275_761304167.dbf

-rw-r-----   1 oraprd   dba          31M Apr  4 01:42 PRDarch1_10276_761304167.dbf

drwxr-xr-x  23 oraprd   dba           42 Apr  4 02:23 ../

-rw-r-----   1 oraprd   dba          28M Apr  4 04:32 PRDarch1_10277_761304167.dbf

-rw-r-----   1 oraprd   dba          28M Apr  4 06:03 PRDarch1_10278_761304167.dbf

-rw-r-----   1 oraprd   dba          30M Apr  4 06:30 PRDarch1_10279_761304167.dbf

-rw-r-----   1 oraprd   dba          28M Apr  4 06:32 PRDarch1_10280_761304167.dbf

-rw-r-----   1 oraprd   dba          28M Apr  4 06:33 PRDarch1_10281_761304167.dbf

-rw-r-----   1 oraprd   dba          28M Apr  4 06:35 PRDarch1_10282_761304167.dbf

-rw-r-----   1 oraprd   dba          28M Apr  4 06:36 PRDarch1_10283_761304167.dbf

-rw-r-----   1 oraprd   dba          28M Apr  4 06:38 PRDarch1_10284_761304167.dbf

-rw-r-----   1 oraprd   dba          28M Apr  4 06:39 PRDarch1_10285_761304167.dbf

-rw-r-----   1 oraprd   dba          28M Apr  4 06:55 PRDarch1_10286_761304167.dbf

-rw-r-----   1 oraprd   dba          35M Apr  4 06:56 PRDarch1_10287_761304167.dbf

-rw-r-----   1 oraprd   dba          37M Apr  4 06:56 PRDarch1_10288_761304167.dbf

-rw-r-----   1 oraprd   dba          35M Apr  4 06:56 PRDarch1_10289_761304167.dbf

-rw-r-----   1 oraprd   dba          40M Apr  4 06:56 PRDarch1_10290_761304167.dbf

-rw-r-----   1 oraprd   dba          40M Apr  4 06:56 PRDarch1_10291_761304167.dbf

-rw-r-----   1 oraprd   dba          32M Apr  4 07:32 PRDarch1_10292_761304167.dbf

-rw-r-----   1 oraprd   dba          27M Apr  4 09:32 PRDarch1_10293_761304167.dbf

-rw-r-----   1 oraprd   dba          28M Apr  4 10:36 PRDarch1_10294_761304167.dbf

drwxr-xr-x   2 oraprd   dba           40 Apr  4 11:04 ./

-rw-r-----   1 oraprd   dba          28M Apr  4 11:04 PRDarch1_10295_761304167.dbf

It shows that the db is performing switch log before the max redo size is reached.

Would you know what could explain this wearied behavior?

Thanks in advance for your answer.

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3 Answers

  • Best Answer
    Apr 05, 2012 at 04:44 PM

    Hello Benoît,

    are you sure that you have an issue with "checkpoint is not complete"? Many customers are mixing this up with the alert log entries "Thread <X> cannot allocate new log, sequence <X> - Private strand flush not complete".

    However regarding your question about reaching the max redo size. There are 3 main reasons for that behavior:

    1. Manual log switch by third party tools
    2. Expected behavior (preemptive redolog switches) like described in sapnote #1627481
    3. Init parameter ARCHIVE_LAG_TARGET (http://docs.oracle.com/cd/E11882_01/server.112/e25513/initparams009.htm#REFRN10003)

    Regards

    Stefan

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    • Hello Stephan,

      Stefan Koehler wrote:

      are you sure that you have an issue with "checkpoint is not complete"? Many customers are mixing this up with the alert log entries "Thread <X> cannot allocate new log, sequence <X> - Private strand flush not complete".

      ...

      1. Manual log switch by third party tools
      2. Expected behavior (preemptive redolog switches) like described in sapnote #1627481
      3. Init parameter ARCHIVE_LAG_TARGET (http://docs.oracle.com/cd/E11882_01/server.112/e25513/initparams009.htm#REFRN10003)

      You are asking if I am sure that it is checkpoint is not complete.

      This is what I see in my alert: Checkpoint not complete.

      Does it answer your question?

      For sure it is not manual switch.

      ARCHIVE_LAG_TARGET is deactivated in my config.

      See you,

  • Apr 12, 2012 at 11:33 AM

    Hello,

    I will resize the redos.

    What are the pros and cons of reducing the log_buffer size as recommended in SAP Note 1627481?

    Thanks in advance for your help.

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    • Hello,

      Leopoldo Capasso wrote:

      Regarding risk to loose a redolog, i just think that you storage and backup strategy must assure that no redolog file must be lost in case of crash or problems of any kind.

      You can have the best storage and backup strategy.

      If you do a rm -r /oracle/PRD you loose everything including the current redo.

      With huge redo and no other tuning, you can loose a lot of production work

      because you have not generated archive redo 😉

      See you,

  • Apr 10, 2012 at 09:19 AM

    Hello Benoit,

    This is a normal behavior and is described in the following notes :

    Note 998675 - Archive log of smaller size than the original redo log

    and Note 1627481 - Preemptive redolog switches in Oracle 11.2 ( that Stephan mentionned ).

    Regarding your "checkpoint is not complete" issue I would :

    First : increase the redolog file size up to 100Mo .

    Second : add redo log groups if this is not enough.

    Regards,

    Steve.

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