Larger redo log file members or more log groups

Oracle 11gR1 RHEL5 64 bit
Hi,
I was wondering what is better from a perfomance tuning perspective. I have log swiches occuring every 2 minutes in our production database. I know definitely that our log file members are too small (100MB). The redo log sizing tool in OEM told me to make it 40G according to the fast_start_mttr_target setting which is set to 600. Now, my question is what is better to do?
1. Increase the size of my current redo log members? Right now there are 4 groups with 2 members in each.
OR
2. Should I create additonal redo log groups (4 more) and then re-rerun the sizing tool or query the v$instance_recovery view?
Which is better? tradeoffs?
Thanks all.

If you want to reduce the number (frequency) of Log Switches, you should increase the size of the Online Redo Logs -- ie create new Log File Groups of a larger size and drop the older ones.
If the issue is "checkpoint not complete" waits, then either
a. Increasing the size of the Log Files
or
b. Increasing the number of Log Files
is doable
Note that if you increase the number but not the size, you still have a checkpoint every N Mbytes -- ie, possibly too frequently !
On the other hand if you increase your size to be very large, at every switch, the Archiver is going to kick in with a large Read + large Write operation -- reading that Redo Log of N GBytes and writing it out to the archive log target location, imposing that additional I/O spike on your system. (Writing to filesystem will go through the FileSystem Buffers so if your database SGA isn't very large and your database performance relies on hitting the FileSystem Buffer Cache to avoid Disk Reads, that performance will be impacted as a large portion of the FileSystem Buffer Cache will be taken over by the Archiver for some time).
Hemant K Chitale
http://hemantoracledba.blogspot.com

Similar Messages

Redo Logs Groups and Members

Hi -
I have a few questions regarding redo log groups and naming conventions I was hoping someone could address or point me to some docs.
I am multiplexing my control file and redo logs across HDDs for an XE installation.
The original logs created at install have the naming form of:
O1_MF_1_462H1GK7_.LOG.
1. What is behind the naming scheme (specifically the _462H1GK7_ section)?
2. Is there a generally recognized naming scheme for adding new group members in XE?
3. I noticed that with any XE install I have done, the redo logs groups default to Group 1 and Group 3, with no Group 2 to be found. Is this normal/required? If not, is it best to add group 2 and then remove group 3? I'm not sure if has much bearing here, but the 10gR2 docs state that skipping group numbers will consume space in the control files.
Thanks in advance for any assistance,
Scott

The odd-looking filename is from using Oracle Managed Files (OMF). You can override the naming scheme or create your own groups and members. Very common to include "redo" in the file name along with group and member identifiers. An example would be:
<path>/redo01a.log
<path>/redo01b.log
<path>/redo02a.log
etc.
You can see group 01 has two members, a and b. Can also include the SID in the file name as well, but that can be identified via the path. 462H1GK7 is a unique identifier generated by Oracle. It has no meaning.
I don't know about XE not creating a group 2. Were there group 2 file(s) left over from a previous install (although the OMF probably would have ignored the existing files)? If creating the files manually, you can use "reuse" to use existing files.

[Consideration] redo logs groups and it's members?

hello Gurus,
Well, the theory written in the book maybe different on the real situation, different company different configuration...
How we determine how many redo logs groups it's should be? And how many members each groups better?
What are the considerations?
Regards,
Nia..

Hi,
You can query v$log_history to check the log switch frequency.
SELECT * FROM ( SELECT * FROM ( SELECT TO_CHAR(FIRST_TIME, 'DD/MM') AS "DAY"
, TO_NUMBER(SUM(DECODE(TO_CHAR(FIRST_TIME, 'HH24'), '00', 1, 0)), '99') "00:00"
, TO_NUMBER(SUM(DECODE(TO_CHAR(FIRST_TIME, 'HH24'), '01', 1, 0)), '99') "01:00"
, TO_NUMBER(SUM(DECODE(TO_CHAR(FIRST_TIME, 'HH24'), '02', 1, 0)), '99') "02:00"
, TO_NUMBER(SUM(DECODE(TO_CHAR(FIRST_TIME, 'HH24'), '03', 1, 0)), '99') "03:00"
, TO_NUMBER(SUM(DECODE(TO_CHAR(FIRST_TIME, 'HH24'), '04', 1, 0)), '99') "04:00"
, TO_NUMBER(SUM(DECODE(TO_CHAR(FIRST_TIME, 'HH24'), '05', 1, 0)), '99') "05:00"
, TO_NUMBER(SUM(DECODE(TO_CHAR(FIRST_TIME, 'HH24'), '06', 1, 0)), '99') "06:00"
, TO_NUMBER(SUM(DECODE(TO_CHAR(FIRST_TIME, 'HH24'), '07', 1, 0)), '99') "07:00"
, TO_NUMBER(SUM(DECODE(TO_CHAR(FIRST_TIME, 'HH24'), '08', 1, 0)), '99') "08:00"
, TO_NUMBER(SUM(DECODE(TO_CHAR(FIRST_TIME, 'HH24'), '09', 1, 0)), '99') "09:00"
, TO_NUMBER(SUM(DECODE(TO_CHAR(FIRST_TIME, 'HH24'), '10', 1, 0)), '99') "10:00"
, TO_NUMBER(SUM(DECODE(TO_CHAR(FIRST_TIME, 'HH24'), '11', 1, 0)), '99') "11:00"
, TO_NUMBER(SUM(DECODE(TO_CHAR(FIRST_TIME, 'HH24'), '12', 1, 0)), '99') "12:00"
, TO_NUMBER(SUM(DECODE(TO_CHAR(FIRST_TIME, 'HH24'), '13', 1, 0)), '99') "13:00"
, TO_NUMBER(SUM(DECODE(TO_CHAR(FIRST_TIME, 'HH24'), '14', 1, 0)), '99') "14:00"
, TO_NUMBER(SUM(DECODE(TO_CHAR(FIRST_TIME, 'HH24'), '15', 1, 0)), '99') "15:00"
, TO_NUMBER(SUM(DECODE(TO_CHAR(FIRST_TIME, 'HH24'), '16', 1, 0)), '99') "16:00"
, TO_NUMBER(SUM(DECODE(TO_CHAR(FIRST_TIME, 'HH24'), '17', 1, 0)), '99') "17:00"
, TO_NUMBER(SUM(DECODE(TO_CHAR(FIRST_TIME, 'HH24'), '18', 1, 0)), '99') "18:00"
, TO_NUMBER(SUM(DECODE(TO_CHAR(FIRST_TIME, 'HH24'), '19', 1, 0)), '99') "19:00"
, TO_NUMBER(SUM(DECODE(TO_CHAR(FIRST_TIME, 'HH24'), '20', 1, 0)), '99') "20:00"
, TO_NUMBER(SUM(DECODE(TO_CHAR(FIRST_TIME, 'HH24'), '21', 1, 0)), '99') "21:00"
, TO_NUMBER(SUM(DECODE(TO_CHAR(FIRST_TIME, 'HH24'), '22', 1, 0)), '99') "22:00"
, TO_NUMBER(SUM(DECODE(TO_CHAR(FIRST_TIME, 'HH24'), '23', 1, 0)), '99') "23:00"
FROM V$LOG_HISTORY
WHERE extract(year FROM FIRST_TIME) = extract(year FROM sysdate)
GROUP BY TO_CHAR(FIRST_TIME, 'DD/MM')
) ORDER BY TO_DATE(extract(year FROM sysdate) || DAY, 'YYYY DD/MM') DESC
) WHERE ROWNUM < 8
regards
jaffy
Edited by: Jaffy on May 14, 2010 12:33 PM

Standby redo log group for particular thread

hi masters,
actually i am performing an experiment to create physical standbyt database on the same machine as my primary database.
i ma going according to 'data guard admin guide'. while section for ading standby redo log group,it says that you have to add standby redo log group to "thread"....
what is this thread? and how can i foind to which thread i have to assign the next redo log group??
how can i find current thread??
what if i dont add "to thread' clause in my statement:-
ALTER DATABASE ADD STANDBY LOGFILE THREAD 5
2> ('/oracle/dbs/log1c.rdo','/oracle/dbs/log2c.rdo') SIZE 500M;
thanks and regards
VD

Vikrant,
First a question: Do you have a RAC instance? If so the paragraph even doesn't apply to you and I'm not sure why you are questioning it.
Secondly
"The THREAD clause is required only if you want to add one or more standby redo log
file groups to a specific primary database thread. If you do not include the THREAD
clause and the configuration uses Real Application Clusters (RAC), Data Guard will
automatically assign standby redo log file groups to threads at runtime as they are
needed by the various RAC instances."
this means you dont have to specify thread for RAC,as it will allocate one according to current thread.
Your conclusion is incorrect.
Where do you read the word 'current'?
Oracle will likely simply make sure each instance has sufficient standby redolog groups, the requirement is 1 standby redolog group per group + 1 extra.
Sybrand Bakker
Senior Oracle DBA

Redo Log Groups

Call me stupid, but for some reason I've decided to get certified as a DBA even though I have always been a developer. Honestly, its not my fault. The choices in the development track are pretty boring...
Anyway, while pouring through the Backup/Recovery documentation, I run across this:
Every database must have at least two online redo log groups.
Each redo log group contains at least one online redo log member,
which is a physical file containing the redo records.I decided to check and see if I have "at least two online redo log groups" for my play database. Now, I am very very confused.
I think this query shows my 3 log members, but for some reason the 1st column makes me think I have 3 log groups:
select group#, member from v$logfile
    GROUP# MEMBER
         3 /var/opt/oracle/oradata/db92/redo03.log
         2 /var/opt/oracle/oradata/db92/redo02.log
         1 /var/opt/oracle/oradata/db92/redo01.logI only know of one place where my online redo is located:
ls $ORACLE_BASE/oradata/db92
redo01.log redo02.log redo03.logCan someone help me figure out if I have one-group and three-members??
Any comments are welcome,
Stan

This information can help you:
Adding Redo Log File Groups: Examples
The following statement adds a redo log file group with two members and identifies it with a GROUP parameter value of 3:
ALTER DATABASE
ADD LOGFILE GROUP 3
('diska:log3.log' ,
'diskb:log3.log') SIZE 50K;
The following statement adds a redo log file group containing two members to thread 5 (in a Real Application Clusters environment) and assigns it a GROUP parameter value of 4:
ALTER DATABASE
ADD LOGFILE THREAD 5 GROUP 4
('diska:log4.log',
'diskb:log4:log');
Dropping Log File Members: Example
The following statement drops one redo log file member added in the previous example:
ALTER DATABASE
DROP LOGFILE MEMBER 'diskb:log3.log';
The following statement drops all members of the redo log file group 3:
ALTER DATABASE DROP LOGFILE GROUP 3;
Adding Redo Log File Group Members: Example
The following statement adds a member to the redo log file group added in the previous example:
ALTER DATABASE
ADD LOGFILE MEMBER 'diskc:log3.log'
TO GROUP 3;
Renaming a Log File Member: Example
The following statement renames a redo log file member:
ALTER DATABASE
RENAME FILE 'diskc:log3.log' TO 'diskb:log3.log';
The preceding statement only changes the member of the redo log group from one file to another. The statement does not actually change the name of the file 'diskc:log3.log' to 'diskb:log3.log'. You must perform this operation through your operating system.
Joel P�rez

Online Redo Log groups

Dear All,
How to check the health of redo log file, we have 200 MB undo tablespace in our production server is it enough for huge transactions. Can I check how much time my redo log file data have been overwritten?
Further in which situation we will add Online Redo Log Groups and which situation we will add Log Members.
My rollback segment is using System tablespace is it recommended?
What is recommendation about 1 redo log group is redo log member or 1 redo log group is multiple redo log members.

Thanks Mr. Nicolas. for your informative guidence.
Can I check how much time my redo log file data have been overwritten?Check v$loghist.
We have 218 records in v$loghist, it means 218 times data have been overwritten, i think its not good. Can you guide me how to rectyify this.
in which situation we will add Online Redo Log GroupsIn case of checkpoint not complete reported into alert.log.
How to findout checkpoint entry in alert.log
which situation we will add Log Members.This is the redolog multiplexing, at least two members for each redolog group.
Ok, Can we do multiplexing for members or just do for groups.
My rollback segment is using System tablespace is it recommended?No.
OK, can we change rollback segments tablespace.
1 redo log group is redo log member or 1 redo log group is multiple redo log membersA minimum of two redolog group with two members for each.
After, it depend of your db activity.
We have just one member for each group and we have three groups, so whats ur recommnedation we will add 1 member in each group.

Why multiplex redo log group ?

Hello,
Why should we multiplex redo log groups if we have only file system which is already mirrored. Is there any one who had an incident when he has only one redo log member per group placed on a mirrored file system but still got corrupted and he felt better to have multiple members even if they reside on the same file system (which is mirrored)
Thanks
Salman

Ansiktet wrote:
EdStevens wrote:
Salman Qureshi wrote:
Hello,
Why should we multiplex redo log groups if we have only file system which is already mirrored. Is there any one who had an incident when he has only one redo log member per group placed on a mirrored file system but still got corrupted and he felt better to have multiple members even if they reside on the same file system (which is mirrored)
Thanks
SalmanThe mirror won't protect you from an SA who deletes '/u01/oradata/redo01.log' because he is running out of space on /u01 and figures its safe to delete a log file.
Or similar types of errors.
The redo and control files are simply too critical to put all your eggs in one basket when planning their protection.:) Thats why you should not use Oracle default .log on redo, instead .dbf or .dbl can be used. THat's why I use the older (pre-10g) default of .rdo for redo logs
However, has this happend anyone for real, that a SA delete Oracle files? Where do you think I came up with the example?
HOw about an SA (or maybe the kind of "fresher" we often see here, Taking a look at a "log" file with notepad?
If he is isnt stupid he should know that Oracle resides on /u01 partion (for example), and should not delete files there without consulting the DBA."should" is the operative word there. There is no accounting for corporate cultures and attitudes.
But end the end, my example was to illustrate that not all problems with redo and control files are mitigated with disk mirroring.

Adding bigger size Redo log groups In RAC , ASM

Hi Folks,
Database version - 10.1.0.4.0
OS version - AIX 5.3
RAC node 2 and ASM
We had 4 redo log groups of lesser size on both nodes.yesterday I added 4 new groups of bigger size using pl/sql developer tool and deleted 2 old redolog groups. But I m not able to delete remaining 2 old groups.
ORA-01567 dropping log2 would have less than 2 log files for instance 1.
Our redolog files are on SAN and both node points to same storage. when I fired this query from command prompt
SELECT v$logfile.member, v$logfile.group#, v$log.status, v$log.bytes
FROM v$log, v$logfile
WHERE v$log.group# = v$logfile.group#;
I got same result for both nodes.
The problem I suspect is that All the 4 new log groups are added to instance 2 and its 2 old grouips are are also deleted.
Now my ques is that :
1. shouild I have added redo log groups separately on both nodes even storage is same for both nodes ?
2. redologs groups are defined separately for each node ?
How should I assign 2 new redo log groups to instance 1 ?
Regards,

Please check:
SQL> select instance_number, instance_name, thread# from gv$instance;
Show Instance with thread ID
SQL> select group#, thread#, members ,status from v$log;
Check number groups in each of thread.
On RAC, you have to add redo log Group each of node (each of thread )
SQL> select group#, thread#, members ,status from v$log;
From your environment ,I think you have 2 nodes = 2 thread
If these're thread 1, 2
So, add redo group should:
Example:
ALTER DATABASE ADD LOGFILE THREAD 1 GROUP 11 ( '+DATA') SIZE 500M;
ALTER DATABASE ADD LOGFILE THREAD 1 GROUP 12 ( '+DATA') SIZE 500M;
ALTER DATABASE ADD LOGFILE THREAD 2 GROUP 13 ( '+DATA') SIZE 500M;
ALTER DATABASE ADD LOGFILE THREAD 2 GROUP 14 ( '+DATA') SIZE 500M;
You should check each thread has >= 2 groups and that group had "INACTIVE" status before drop:
SQL> select group#, thread#, members ,status from v$log;
My Idea, you should have 3 redo log groups for each node(thread)
Good Luck

Unable to drop a Redo Log Group

Hi,
My database is running on version 11.1.0.7 on OEL platform.
I am trying to delete one of the Active Redo Log Group, it fails with the below error. Could someone please help me fix this issue?
SQL > select * from v$log;
    GROUP#    THREAD# SEQUENCE#      BYTES    MEMBERS ARCHIVED STATUS                                           FIRST_CHANGE# FIRST_TIME
        10          1       8017 524288000          2 YES       INACTIVE                                            1.2120E+13 17-JUN-2012 19:43:49
        11          1       8018 524288000          2 YES       INACTIVE                                            1.2120E+13 18-JUN-2012 06:49:45
        12          1       8019 524288000          2 YES       INACTIVE                                            1.2120E+13 18-JUN-2012 16:56:43
        13          1       8021 524288000          2 YES       INACTIVE                                            1.2120E+13 18-JUN-2012 23:18:07
        14          1       8020 524288000          2 YES       INACTIVE                                            1.2120E+13 18-JUN-2012 23:14:27
        15          1       8022 524288000          2 NO        CURRENT                                             1.2120E+13 19-JUN-2012 01:07:27
        16          2       6835 524288000          2 YES       INACTIVE                                            1.2120E+13 18-JUN-2012 23:15:46
        17          2       6836 524288000          2 YES       INACTIVE                                            1.2120E+13 18-JUN-2012 23:18:04
        18          2       6837 524288000          2 YES       INACTIVE                                            1.2120E+13 18-JUN-2012 23:20:22
        19          2       6838 524288000          2 YES       INACTIVE                                            1.2120E+13 18-JUN-2012 23:22:38
        20          2       6839 524288000          2 NO        CURRENT                                             1.2120E+13 19-JUN-2012 01:07:24
        21          2       6832 524288000          2 YES       INACTIVE                                            1.2120E+13 18-JUN-2012 23:11:45
        22          3       3771 524288000          2 YES       INACTIVE                                            1.2103E+13 09-SEP-2011 22:04:11
        23          3       3772 524288000          2 YES       INACTIVE                                            1.2103E+13 09-SEP-2011 23:55:55
        24          3       3773 524288000          2 YES       ACTIVE                                              1.2103E+13 09-SEP-2011 23:55:59
        25          3       3766 524288000          2 YES       INACTIVE                                            1.2103E+13 08-SEP-2011 22:05:29
        26          3       3767 524288000          2 YES       INACTIVE                                            1.2103E+13 08-SEP-2011 22:05:50
        27          3       3768 524288000          2 YES       INACTIVE                                            1.2103E+13 09-SEP-2011 14:02:05
SQL > archive log list;
Database log mode              Archive Mode
Automatic archival             Enabled
Archive destination            /archive/MYCSMA/MYCSMA2
Oldest online log sequence     6832
Next log sequence to archive   6839
Current log sequence           6839
SQL > archive log all;
ORA-00271: there are no logs that need archiving
SQL > ALTER SYSTEM ARCHIVE LOG GROUP 24;
ALTER SYSTEM ARCHIVE LOG GROUP 24
ERROR at line 1:
ORA-16013: log 24 sequence# 3773 does not need archiving
SQL > alter database drop LOGFILE group 24;
alter database drop LOGFILE group 24
ERROR at line 1:
ORA-01623: log 24 is current log for instance MYCSMA3 (thread 3) - cannot drop
ORA-00312: online log 24 thread 3: '/u247/oradata/MYCSMA/redo24_1.log'
ORA-00312: online log 24 thread 3: '/u247/oradata/MYCSMA/redo24_2.log'This was previously a 3 node RAC and when it was moved to a different machine, it got build with a 2-node RAC.
Hence thread 3 is no more required. Thats why I am planning to drop these Redo Log Groups.
Thanks!

Hi;
All information cover at:
NOTE:102995.1 - Maintenance of Online Redo Log Groups and Members
Regard
Helios

Confused about standby redo log groups

hi masters,
i am little bit confuse about creating redo log group for standby database,as per document number of standby redo group depends on following equation.
(maximum number of logfiles for each thread + 1) * maximum number of threads
but i dont know where to fing threads? actually i would like to know about thread in deep.
how to find current thread?
thanks and regards
VD

is it really possible that we can install standby and primary on same host??
yes its possible and i have done it many times within the same machine.
For yours confusion about spfile ,i agree document recommend you to use spfile which is for DG broker handling if you go with DG borker in future only.
There is no concern spfile using is an integral step for primary and standby database implementation you can go with pfile but good is use spfile.Anyhow you always keep pfile on that basis you created spfile,i said you make an entry within pfile then mount yours standby database with this pfile or you can create spfile from this pfile after adding these parameter within pfile,i said cause you might be adding this parmeter from SQL prompt.
1. logs are not getting transfered(even i configure listener using net manager)
2.logs are not getting archived at standby diectory.
3.'ALTER DATABASE RECOVER MANAGED STANDBY DATABASE DISCONNECT FROM SESSION' NEVER COMPLETE ITS RECOVERY
4. when tried to open database it always note it 'always' said system datafile is not from sufficiently old backup.
5.i tried 'alter database recover managed standby database camncel' also.Read yours alert log file and paste the latest log here..
Khurram

After increasing redo log groups we are getting given alerts continvously

earlier having 6 redo log groups with 32 MB.but 7 days back our database was hangs .no one was able to login into sqlplus except sys user ,but not able to perform any dml operation.after rebooting our 2-node RAC instances it was running fine nearly about 6-7 hrs and again hangs.we did 4-5 times and same thing happend again and again.so we had added more redo logs of 100 MB size and removed previous one.then our hangs problem resolved but continvously getting given things in alert logs for both RAC instances(9.2.0.8).our os is linux
{color:#ff0000}Wed Dec 3 05:04:31 2008
ARC1: Completed archiving log 15 thread 1 sequence 282036
ARC1: Evaluating archive log 17 thread 1 sequence 282037
ARC1: Unable to archive log 17 thread 1 sequence 282037
Log actively being archived by another process
ARC1: Evaluating archive log 13 thread 1 sequence 282038
ARC1: Beginning to archive log 13 thread 1 sequence 282038
Creating archive destination LOG_ARCHIVE_DEST_2: 'SBMEMS'
Creating archive destination LOG_ARCHIVE_DEST_1: '/MemsArchive/0001_0000282038.arc'
Wed Dec 3 05:04:31 2008
Thread 1 advanced to log sequence 282040
Current log# 15 seq# 282040 mem# 0: /MemsRedoA/redo15_1.log
Current log# 15 seq# 282040 mem# 1: /MemsRedoB/redo15_2.log
Wed Dec 3 05:05:21 2008
ARC1: Completed archiving log 13 thread 1 sequence 282038
ARC1: Evaluating archive log 17 thread 1 sequence 282037
{color}{color:#ff0000}*ARC1: Unable to archive log 17 thread 1 sequence 282037*
Log actively being archived by another process
ARC1: Evaluating archive log 18 thread 1 sequence 282039
ARC1: Beginning to archive log 18 thread 1 sequence 282039
Creating archive destination LOG_ARCHIVE_DEST_2: 'SBMEMS'
Creating archive destination LOG_ARCHIVE_DEST_1: '/MemsArchive/0001_0000282039.arc'
Wed Dec 3 05:05:21 2008
ARC0: Completed archiving log 17 thread 1 sequence 282037
ARC0: Evaluating archive log 18 thread 1 sequence 282039
ARC0: Unable to archive log 18 thread 1 sequence 282039
Log actively being archived by another process
ARC0: Evaluating archive log 18 thread 1 sequence 282039
{color}{color:#ff0000}*ARC0: Unable to archive log 18 thread 1 sequence 282039*
Log actively being archived by another process
ARC0: Evaluating archive log 18 thread 1 sequence 282039
{color}{color:#ff0000}*ARC0: Unable to archive log 18 thread 1 sequence 282039*
Log actively being archived by another process
ARC0: Evaluating archive log 18 thread 1 sequence 282039
ARC0: Unable to archive log 18 thread 1 sequence 282039
Log actively being archived by another process
ARC0: Evaluating archive log 18 thread 1 sequence 282039
ARC0: Unable to archive log 18 thread 1 sequence 282039
Log actively being archived by another process
ARC0: Evaluating archive log 18 thread 1 sequence 282039
ARC0: Unable to archive log 18 thread 1 sequence 282039
Log actively being archived by another process
Wed Dec 3 05:05:49 2008
ARC1: Completed archiving log 18 thread 1 sequence 282039
Wed Dec 3 09:01:02 2008
Thread 1 advanced to log sequence 282041
Current log# 17 seq# 282041 mem# 0: /MemsRedoA/redo17_1.log
Current log# 17 seq# 282041 mem# 1: /MemsRedoB/redo17_2.log
Wed Dec 3 09:01:02 2008
ARC1: Evaluating archive log 15 thread 1 sequence 282040
ARC1: Beginning to archive log 15 thread 1 sequence 282040
Creating archive destination LOG_ARCHIVE_DEST_2: 'SBMEMS'
Creating archive destination LOG_ARCHIVE_DEST_1: '/MemsArchive/0001_0000282040.arc'
Wed Dec 3 09:01:29 2008
ARC0: Evaluating archive log 15 thread 1 sequence 282040
{color}{color:#ff0000}*ARC0: Unable to archive log 15 thread 1 sequence 282040*
Log actively being archived by another process
Wed Dec 3 09:01:37 2008
ARC1: Completed archiving log 15 thread 1 sequence 282040
{color}ORADB1:MEMS1:oracle$
please suggest solution for this.
Thanks

As Sybrand pointed out, this msg can be ignored. It clearly states that a given arch process cannot archive a given redo because that redo is already being handled by a different arch process. If you follow your alert log a little further, you'll see that the referenced thread is eventually completed.
I'd be curious to see the alert log from when you were locked up and only sysdba could log on. See what led you to believe that adding more redo log groups would solve your problem.

Online redo log group needed??

hey guys!
Am about to recreate the clone file of the clone db, open it using recover it until cancel using backup controlfile and apply all necessary archive logs!
My question is, does ai need to have online redo log group of the production db? since ai have all the archive log, so ai think while recraeting the control file, online redo log group will be created too?
Thanks!

while recraeting the control file, online redo log group will be created tooWhile creating control file, online redo log group doesn't get created. After applying all the archivel logs you have to open the database with RESET LOG option and then oracle will create redo logs for you.
Best of Luck !!
Daljit Singh

Delete all redo log groups

Friends,
Suddenly I have to delete all of my redo log groups (REDO01.LOG,REDO02.LOG,REDO03.LOG) from my database . Now I cannot open my database . I am using Oracle 10g database . I have no cold backup of my database but have a RMAN backup . Now How can I restore my redo log groups .
Can anybody plz help me .. ...

if you are working in archive mode
SQL> startup
ORACLE instance started.
Total System Global Area 272629760 bytes
Fixed Size 1290136 bytes
Variable Size 213909608 bytes
Database Buffers 50331648 bytes
Redo Buffers 7098368 bytes
Database mounted.
ORA-00313: open failed for members of log group 1 of thread 1
ORA-00312: online log 1 thread 1:
'D:\ORACLE\PRODUCT\10.2.0\ORADATA\PEEGT\REDO01.LOG'
SQL> recover database until cancel;
Media recovery complete.
SQL> alter database open resetlogs;
Database altered.
Backup your database...

REDO LOG GROUP QUESTION

I was reading an article and it said
the distance(in bytes) between the checkpoint position in a redolog group and the end of the current redolog group can never be more then 90 % of the size of the smallest redo log group
Can someone elaborate this

I'm not sure what you want to elaborate on, but yes, it's true. If your redo logs are 100MB in size, and nothing else causes a checkpoint to take place, you'll have a checkpoint issued when you hit the 90MB mark. The idea is simply that you don't want to sit there doing nothing at all and then bang! the logs switch and you have to go hell-for-leather performing a massive checkpoint, all the while praying more log switches don't mean that you're threatening to catch up with yourself (at which point you'd have the 'thread unable to advance to log...' problem). By implementing the 90% rule, the idea is that your log switch, at worst, will cause a "10%-sized" checkpoint, which should be bearable.
Of course, the situation is made more complex by the fact that other things DO kick in and cause their own checkpoints, so the interaction between -for example, FAST_START_MTTR_TARGET and the 90% rule can get, er, 'interesting'.

Usage of Redo Log Groups & Disk Contention

Hi,
I have a peculiar problem here.
I have the redo log groups/members configured in the following manner.Please note that the disks are in the A-B-A-B-A-B sequence for successive redo groups.
GROUP#      MEMBER
11      /origlogA/log_g11m1.dbf
11      /mirrlogA/log_g11m2.dbf
12      /origlogB/log_g12m1.dbf
12      /mirrlogB/log_g12m2.dbf
13      /origlogA/log_g13m1.dbf
13      /mirrlogA/log_g13m2.dbf
14      /origlogB/log_g14m1.dbf
14      /mirrlogB/log_g14m2.dbf
15      /origlogA/log_g15m1.dbf
15      /mirrlogA/log_g15m2.dbf
16      /origlogB/log_g16m1.dbf
16      /mirrlogB/log_g16m2.dbf
17      /origlogA/log_g17m1.dbf
17      /mirrlogA/log_g17m2.dbf
18      /origlogB/log_g18m1.dbf
18      /mirrlogB/log_g18m2.dbf
19      /origlogA/log_g19m1.dbf
19      /mirrlogA/log_g19m2.dbf
20      /origlogB/log_g20m1.dbf
20      /mirrlogB/log_g20m2.dbf
21      /origlogA/log_g21m1.dbf
21      /mirrlogA/log_g21m2.dbf
22      /origlogB/log_g22m1.dbf
22      /mirrlogB/log_g22m2.dbf
23      /origlogA/log_g23m1.dbf
23      /mirrlogA/log_g23m2.dbf
24      /origlogB/log_g24m1.dbf
24      /mirrlogB/log_g24m2.dbf
But oracle uses these groups in a zig-zag manner(pls refer the list below).Here, after group# 15, it is group# 11 , which is used. And the members of these two groups are in the same set of disks ie; "/origlogA and /mirrlogA"
(Note:The following result is ordered by sequence #)
GROUP# SEQUENCE#      MEMBER
16      263076           /origlogB/log_g16m1.dbf
16      263076           /mirrlogB/log_g16m2.dbf
17      263077           /origlogA/log_g17m1.dbf
17      263077           /mirrlogA/log_g17m2.dbf
18      263078           /origlogB/log_g18m1.dbf
18      263078           /mirrlogB/log_g18m2.dbf
19      263079           /origlogA/log_g19m1.dbf
19      263079           /mirrlogA/log_g19m2.dbf
20      263080           /origlogB/log_g20m1.dbf
20      263080           /mirrlogB/log_g20m2.dbf
21      263081           /origlogA/log_g21m1.dbf
21      263081           /mirrlogA/log_g21m2.dbf
22      263082           /origlogB/log_g22m1.dbf
22      263082           /mirrlogB/log_g22m2.dbf
23      263083           /origlogA/log_g23m1.dbf
23      263083           /mirrlogA/log_g23m2.dbf
24      263084           /origlogB/log_g24m1.dbf
24      263084           /mirrlogB/log_g24m2.dbf
13      263085           /origlogA/log_g13m1.dbf
13      263085           /mirrlogA/log_g13m2.dbf
14      263086           /origlogB/log_g14m1.dbf
14      263086           /mirrlogB/log_g14m2.dbf
15      263087           /origlogA/log_g15m1.dbf
15      263087           /mirrlogA/log_g15m2.dbf
11      263088           /origlogA/log_g11m1.dbf
11      263088           /mirrlogA/log_g11m2.dbf
12      263089           /origlogB/log_g12m1.dbf
12      263089           /mirrlogB/log_g12m2.dbf
Is there anyway, which we can force oracle to use the log groups in the right succession of log groups ? (like 11-12-13-14-15-16-17-18-19-20 etc.).
I want to make sure that there will be no chances of contention, due to the "archiving of the offline redo log & LGWR writing to the online redo log" happening on the same disk.
Thanks in advance,
Don

Hi,
There's no way to achieve what you're trying to do except:
1/ switch logfile till the current group is the last one.
2/ drop groups from 1 to (last - 2)
3/ create groups 1, 2, 3 (or 11, 12, 13, 14, ... don't care)
4/ Switch logfile Twice
5/ Alter system checkpoint
6/ Drop the former 2 or 3 remaining groups (19, 20, 21, ...)
7/ Recreate them.
But i'd like to point that having them go in order is perfectly useless.
And that you're a priori doing something dangerous. Having your log members on the same disk for the different groups. usually I'd choose to
. Put member 1 on disk 1
. Put member 2 on disk 2
. Increase the number of archiver processes
. ensure disk 1 and 2 are not RAID disk(click)
Regards,
Yoann.

Larger redo log file members or more log groups

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