Recommended os block size for redo log

Hi
Platform AIX
Oracle 10.2.0.4
Is there any recommended filesystem blocksize where redo log should be placed?
We have tested with 512 bytes and 4096 bytes. We got better performance on 512 bytes in terms of avg wait on log file sync.
Is there oracle/Aix recommendation on the same?

978881 wrote:
Hi
Platform AIX
Oracle 10.2.0.4
Is there any recommended filesystem blocksize where redo log should be placed?
We have tested with 512 bytes and 4096 bytes. We got better performance on 512 bytes in terms of avg wait on log file sync.
Is there oracle/Aix recommendation on the same?The recommendation is to create redo logs on a mount with agblk=512bytes. Please refer following link(page 60) which is a oracle+IBM technical brief:
http://www-03.ibm.com/support/techdocs/atsmastr.nsf/5cb5ed706d254a8186256c71006d2e0a/bae31a51a00fa0018625721f00268dc4/$FILE/Oracle%20Architecture%20and%20Tuning%20on%20AIX%20(v%202.30).pdf
Regards,
S.K.

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hi,
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How often should a database archive its logs
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"If the FAST_START_MTTR_TARGET parameter is set to limit the instance recovery time, Oracle automatically tries to checkpoint as frequently as necessary. Under this condition, the size of the log files should be large enough to avoid additional checkpointing due to under sized log files. The optimal size can be obtained by querying the OPTIMAL_LOGFILE_SIZE column from the V$INSTANCE_RECOVERY view. You can also obtain sizing advice on the Redo Log Groups page of Oracle Enterprise Manager Database Control."
Source:http://download-west.oracle.com/docs/cd/B13789_01/server.101/b10752/build_db.htm#19559
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Source:Re: Redo Log Size in R12
HTH
Girish Sharma

ORA-00349: failure obtaining block size for '+Z' in Oracle XE

Hello,
I am attempting to move the online redo log files to a new flash recovery area location created on network drive "Z" ( Oracle Database 10g Express Edition Release 10.2.0.1.0).
When I run @?/sqlplus/admin/movelogs; in SQL*Plus as a local sysdba, I get the following errors:
ERROR at line 1:
ORA-00349: failure obtaining block size for '+Z'
ORA-06512: at line 14
Please let me know how to go about resolving this issue.
Thank you.
See below for detail:
Connected.
SQL> @?/sqlplus/admin/movelogs;
SQL> Rem
SQL> Rem $Header: movelogs.sql 19-jan-2006.00:23:11 banand Exp $
SQL> Rem
SQL> Rem movelogs.sql
SQL> Rem
SQL> Rem Copyright (c) 2006, Oracle. All rights reserved.
SQL> Rem
SQL> Rem NAME
SQL> Rem movelogs.sql - move online logs to new Flash Recovery Area
SQL> Rem
SQL> Rem DESCRIPTION
SQL> Rem This script can be used to move online logs from old online
log
SQL> Rem location to Flash Recovery Area. It assumes that the database
SQL> Rem instance is started with new Flash Recovery Area location.
SQL> Rem
SQL> Rem NOTES
SQL> Rem For use to rename online logs after moving Flash Recovery
Area.
SQL> Rem The script can be executed using following command
SQL> Rem sqlplus '/ as sysdba' @movelogs.sql
SQL> Rem
SQL> Rem MODIFIED (MM/DD/YY)
SQL> Rem banand 01/19/06 - Created
SQL> Rem
SQL>
SQL> SET ECHO ON
SQL> SET FEEDBACK 1
SQL> SET NUMWIDTH 10
SQL> SET LINESIZE 80
SQL> SET TRIMSPOOL ON
SQL> SET TAB OFF
SQL> SET PAGESIZE 100
SQL> declare
2 cursor rlc is
3 select group# grp, thread# thr, bytes/1024 bytes_k
4 from v$log
5 order by 1;
6 stmt varchar2(2048);
7 swtstmt varchar2(1024) := 'alter system switch logfile';
8 ckpstmt varchar2(1024) := 'alter system checkpoint global';
9 begin
10 for rlcRec in rlc loop
11 stmt := 'alter database add logfile thread ' ||
12 rlcRec.thr || ' size ' ||
13 rlcRec.bytes_k || 'K';
14 execute immediate stmt;
15 begin
16 stmt := 'alter database drop logfile group ' || rlcRec.grp;
17 execute immediate stmt;
18 exception
19 when others then
20 execute immediate swtstmt;
21 execute immediate ckpstmt;
22 execute immediate stmt;
23 end;
24 execute immediate swtstmt;
25 end loop;
26 end;
27 /
declare
ERROR at line 1:
ORA-00349: failure obtaining block size for '+Z'
ORA-06512: at line 14
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888442 wrote:
I am trying to drop and recreate ONLINE redo logs on my STANDB DATABASE (11.1.0.7)., but i am getting the below error.
On primary, we have done the changes., ie we added new logfile with bigger size and 3 members. When trying to do the same on Standby we are getting this error.
Our database is in Active DG Read only mode and the oracle version is 11.1.0.7.
I have deffered the log apply and cancelled the managed recovery, and dg is in manual mode.
SQL> alter database Add LOGFILE GROUP 4 ('+DT_DG1','+DT_DG2','+DT_DG3') SIZE 1024M;
alter database Add LOGFILE GROUP 4 ('+DT_DG1','+DT_DG2','+DT_DG3') SIZE 1024M
ERROR at line 1:
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On standby only standby redo log files will be used. Not sure what you are trying to do.
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sys@ORCL> select member from v$logfile;
MEMBER
C:\ORACLE\ORADATA\ORCL\REDO03.LOG
C:\ORACLE\ORADATA\ORCL\REDO02.LOG
C:\ORACLE\ORADATA\ORCL\REDO01.LOG
sys@ORCL> alter database add logfile group 4 (
2     'C:\ORACLE\ORADATA\ORCL\redo_g01a.log',
3     'C:\ORACLE\ORADATA\ORCL\redo_g01b.log',
4     'C:\ORACLE\ORADATA\ORCL\redo_g01c.log') size 10m;
Database altered.
sys@ORCL> select member from v$logfile;
MEMBER
C:\ORACLE\ORADATA\ORCL\REDO03.LOG
C:\ORACLE\ORADATA\ORCL\REDO02.LOG
C:\ORACLE\ORADATA\ORCL\REDO01.LOG
C:\ORACLE\ORADATA\ORCL\REDO_G01A.LOG
C:\ORACLE\ORADATA\ORCL\REDO_G01B.LOG
C:\ORACLE\ORADATA\ORCL\REDO_G01C.LOG
6 rows selected.
sys@ORCL>
Your profile:-
888442
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Handle:      888442
Status Level:      Newbie
Registered:      Sep 29, 2011
Total Posts:      12
Total Questions:      8 (7 unresolved)
Close the threads if answered, Keep the forum clean.

Optimal size of redo log

Hi all,
Recently we migrated from 9.2.0.4 to 10.2.0.4 and database performance is slow in newer version, on checking alert log we found this:-
Thread 1 cannot allocate new log, sequence 1779 Checkpoint not complete
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Current log# 1 seq# 1779 mem# 0: /oradata/lipi/redo01.log
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Current log# 2 seq# 1780 mem# 0: /oradata/lipi/redo02.log
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Current log# 2 seq# 1786 mem# 0: /oradata/lipi/redo02.log
Current log# 2 seq# 1786 mem# 1: /oradata/lipi/redo02a.log Wed Mar 10 15:31:22 2010 Thread 1 cannot allocate new log, sequence 1787 Private strand flush not complete
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Current log# 3 seq# 1787 mem# 0: /oradata/lipi/redo03.log
Current log# 3 seq# 1787 mem# 1: /oradata/lipi/redo03a.log Wed Mar 10 15:31:47 2010 Thread 1 advanced to log sequence 1788 (LGWR switch)
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Current log# 4 seq# 1788 mem# 1: /oradata/lipi/redo04a.log
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Respected Sir,
So many things are going to popular without evidence, experts comments and even cross marking by docs. I would like to suggest to add one more chapter in next oracle release docs something like:
"Myths in Oracle" and i hope following should be there:
1. Put indexes in seperate tablespace to achieve good performance.
2. Different block size issues and its pros and cons.
3. Index scan is always best then full table scan; means if optimizer is not using index means there is something "fishy" with either query or database.
4. Certification is the measurement of good knowledge in oracle.
5. count(1) or count(*) is faster than each other.
(difference between count(*) and count(1) and count(column name)
6. Views are slow
(Do you believe that "views are slow" is a myth
7. BCHR is meaningful indicator for the performance of the database.
(I do'nt want to put the link, because that thread is .... )
8. And this thread i.e. redo log should be large enough to have at least 20 minutes of data.
Sir, since i am regular reader of your site, blog and book; if you please spare some time on above or more myths in oracle; i hope it will help the whole oracle dba community who is something like in a very big and dark hall with lot of doors and windows (as i am).
Kind Regards
Girish Sharma
Edited by: Girish Sharma on Mar 11, 2010 6:27 PM
And i got the useful link of your site please too:
http://www.jlcomp.demon.co.uk/myths.html

Choosing block size for RAID 0 & Final Cut

Hi.
I now have 3 500GB internal Seagate drives in bays 2/3/4 and want to make a striped 1.5TB RAID to use with Final Cut Studio 2. The help page talks about choosing a "large" data block size for use with video, but makes no specific size suggestion. What value would you recommend that I select for the block size? I haven't been in there yet so I don't know what the choices are.
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Message was edited by: FredGarvin
Message was edited by: FredGarvin

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" You are not using large blocksizes for your index tablespaces. Oracle research proves that indexes will build flatter tree structures in larger blocksizes.
Is this a generic statement that I can use for all tables or indexes? I also have batch and online activity. My primary target is batch and it should not impact online. Not sure if both have common tables.
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What about tables, what is the success criterion for tables. can we use the same flat tree str criterion? Is there a query for this?

user3390467 wrote:
" You are not using large blocksizes for your index tablespaces. Oracle research proves that indexes will build flatter tree structures in larger blocksizes.
Is this a generic statement that I can use for all tables or indexes? This is a generic statement used by some consultants. Unfortunately, it is riddled with exceptions and other considerations.
One consultant in particular seems to have anecdotal evidence that using different block sizes for index (big) and data (small) can yield almost miraculous improvements. However, that can not be backed up due to NDA. Many of the rest of us can not duplicate the improvements, and indeed some find situations where that results in a degradation (esp with high insert/update rates from separated transactions).
I also have batch and online activity. My primary target is batch and it should not impact online. Not sure if both have common tables.
How to find the current block size used for tables and index? is there a v$parameter query?
What is an optimal block size value for batch?
How do I know when flatter tree str has been achieved using above changes? Is there a query to determine this?
What about tables, what is the success criterion for tables. can we use the same flat tree str criterion? Is there a query for this?I'd strongly recommend that you
1) stop using generic tools to analyze specific problems
2) define you problem in detail ()what are you really trying to accomplish - seems like performance tuning, but you never really state that)
3) define the OS and DB version - in detail. Give rev levels and patch levels.
If you are having a serious performance issue, I strongly recommend you look at some performance tuning specialists like "http://www.method-r.com/", "http://www.miracleas.dk/", "http://www.hotsos.com/", "http://www.pythian.com/", or even Oracle's Performance Tuning consultants. Definitely worth the price of admission.

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Hi,
I launched health Chack of TOAD on my Database and I had :
! "Checkpoint not complete" errors: 1744
! (consider adding or increasing size of redo logs to resolve this)
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2-increase a logfile ?
Many thanks.

The size is set when you create the redo logs you can not adjust this size without going through a lot of hoops. One method of increasing the size is described in metalink note: 1035935.6
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Retention for redo logs

Hi ,
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936639 wrote:
Hi ,
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http://docs.oracle.com/cd/E11882_01/backup.112/e10642/rcmconfb.htm#i1019318
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Many thanks, and Happy Holidays to all!

If it is just scratch, run some benchmarks with it set to 128k and 256k and see how it feels with each. The default is too small, though some find it acceptable for small images. For larger files you want larger - and for PS scratch you definitely want 128 or 256k.

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Hi Eddie...
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Recommended os block size for redo log

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