new with OMF online redo log files

Similar Questions

• Redo log entries to the online redo log files

  Hello

  I'm a little confused about the redo log entries.

  I learned that LGWR writes redo log entries in the SGA, in redo log files in the following situation:

  -3 seconds after the last validation

  -redo log buffer has 1 MB

  -redo log buffer data 1/3

  When I take a transaction and if I change the wrong data, I have to cancel this transaction BUT the right now,

  What happens if the LGWR writes redo log disk entries?

  Is the bad transaction committed at all times?

  2791011 wrote:

  Hello

  I'm a little confused about the redo log entries.

  I learned that LGWR writes redo log entries in the SGA, in redo log files in the following situation:

  -3 seconds after the last validation

  -redo log buffer has 1 MB

  -redo log buffer data 1/3

  When I take a transaction and if I change erroneous data, I have to cancel this transaction at this time, BUT

  What happens if the LGWR writes redo log disk entries?

  Is the bad transaction committed at all times?

  DML changes are "permanent" after that VALIDATION is issued.

  When any COMMIT is issued, then changes can be undone.

• I have to create the new group for waiting for redo log files?

  I have 10 group of files redo log with 2 members of each group for my primary database, I need to create new group for redo log files for the database of relief pending

  Group # members

  ==============

  1              2

  2              2

  3             2

  4             2

  5             2

  6             2

  7             2

  8             2

  9             2

  2 of 10

  If so, the following statement is correct? or nto

  ALTER DATABASE ADD STANDBY LOGFILE GROUP 1 ('D:\Databases\epprod\StandbyRedoLog\REDO01.) LOG',D:\Databases\epprod\StandbyRedoLog\REDO01_1.log');

  Please correct me if am doin wrong

  because when I run the statement I have error message saying: the group is already created.

  Thanks John

  I just found the answer

  Yes, it of recomeded to add the new group, for instnace if I have 10 group of 1 to 10, then the wait should be from 11 to 20

  Thanks I found the answer.

• Cold backup with online redo logs

  I'm working on 10G in AIX for a single instance
  It's just a general db backup & restore issue, but I have something confused.
  
  I'll take a cold backup with my database ARCHIVELOG.
  No wonder why make a backup of cold because it's a test database that can suffer from loss of data and the time during backup.
  I read some guides. They all mentioned to back up all the data files and control files.
  When restoring I copy all saved data files and control files to the default location.
  Then mount boot;
  Is the last step before opening the database recover database until cancel;
  For the acknowledgement, I do the database recovery command, because again the online newspapers were not saved, so we must recover in order to reset the redo logs.
  For my question, I would be in a position of order recovery of database, then directly the database starts, if I backed up online redo logs and copy the default location when restoring?
  However, I have read a lot of documents that mentions that it is not proposed to backup online redo logs. Is it simply the case that ONLY applied in the backup hot? Do you think all that for my case, cold backup online redo logs is recommended?
  
  Thank you all

  Hello

  read the response of Hemant ==> Re: restoration of noarchive

  Anand

• Invalid state online redo log on backup database

  Hi all
  
  I'm new here with a little problem with Oracle Dataguard.
  After the double, redo log files and log files online pending
  are equal in major databases and relief.
  But now, in the database of relief, some redologs online are missing.
  So, I created files of online journals on the standby database.
  But the State is not valid:
  

      GROUP# STATUS  TYPE    MEMBER                                                                           IS_
  ---------- ------- ------- -------------------------------------------------------------------------------- ---
           1 INVALID ONLINE  +DATA/PROJ_STD/onlinelog/group_1.392.123263579                                  NO
           1         ONLINE  +FRA/PROJ_STD/onlinelog/group_1.948.123234493                                   YES
           2         ONLINE  +FRA/PROJ_STD/onlinelog/group_2.852.123234495                                   YES
           2 INVALID ONLINE  +DATA/PROJ_STD/onlinelog/group_2.393.123263607                                  NO
           3         ONLINE  +FRA/PROJ_STD/onlinelog/group_3.946.123234495                                   YES
           3 INVALID ONLINE  +DATA/PROJ_STD/onlinelog/group_3.394.123263613                                  NO
           4 INVALID ONLINE  +DATA/PROJ_STD/onlinelog/group_4.395.123263615                                  NO
           4         ONLINE  +FRA/PROJ_STD/onlinelog/group_4.933.123234497                                   YES
           5         STANDBY +FRA/PROJ_STD/onlinelog/group_5.989.123262059                                   NO
           5         STANDBY +DATA/PROJ_STD/onlinelog/group_5.387.123262055                                  NO
           6         STANDBY +FRA/PROJ_STD/onlinelog/group_6.990.123262075                                   NO
           6         STANDBY +DATA/PROJ_STD/onlinelog/group_6.388.123262073                                  NO
           7         STANDBY +DATA/PROJ_STD/onlinelog/group_7.389.123262081                                  NO
           7         STANDBY +FRA/PROJ_STD/onlinelog/group_7.991.123262085                                   NO
           8         STANDBY +DATA/PROJ_STD/onlinelog/group_8.390.123262091                                  NO
           8         STANDBY +FRA/PROJ_STD/onlinelog/group_8.992.123262093                                   NO
           9         STANDBY +DATA/PROJ_STD/onlinelog/group_9.391.123262103                                  NO
           9         STANDBY +FRA/PROJ_STD/onlinelog/group_9.993.123262105                                   NO

  the newspaper of the alerts:
  

  ORA-00313: open failed for members of log group 1 of thread 1
  ORA-00313: open failed for members of log group 2 of thread 1
  ORA-00313: open failed for members of log group 3 of thread 1
  ORA-00313: open failed for members of log group 4 of thread 1

  Is this correct? What's wrong? What I can do to solve this problem and all newspapers in restoration online in the two databases are equal?
  
  Thank you very much!!!

  Hello;

  Check out this note first:

  ORA-00313, ORA-00312, ORA-27037 Standby Database [601835.1 ID]

  OR

  On implementing standby

  ALTER DATABASE RECOVER MANAGED STANDBY DATABASE CANCEL;

  And then, for each group of newspaper

  change the database group claire logfile 1;

  After this verification, the v$ log view to confirm the size and status.

  Also check v$ standby_log and make sure that you have the day before newspapers too.

  Finally, check the alerts log and make sure that no more errors have occurred after that you have disabled the logfile group.

  Best regards

  mseberg

  Published by: mseberg on November 3, 2011 18:41

• Loss of all Redo Log files

  Hello

  It's for testing purposes and practice of recovery scenarios. Database is in log mode archive. My question would be on the scenario in which we loose that redo all online log files available.

  Now after doing a lot of research on the internet I could find two scenarios.

  CASES1

  My recovery logs have been lost. But I could stop normal or immediate of the database. In this case I could perform incomplete recovery using my archived logs and re create the logs online redo with the resetlogs option.

  CAS2 (my question)

  My recovery logs have been lost and the system crashed. Now, oracle would need perform a recovery of proceeding on re start, however there is no present setpoint recovery to perform this restore.

  Is it not possible to recover the database, even if I have a valid backup? If there is, how do you do that?

  Thank you

  If you lose all copies of online redo logs, you lost all those transactions. Data files may or may not have some or all of the data of those redo logs. You need restore the database and retrieve it at the point in time of the last series of archive logs (at the latest) and go from there.

  But guess what? Oracle expected that someone might have a question like that, and actually (gasp) has documented the scenario:

  http://docs.Oracle.com/CD/B19306_01/backup.102/b14191/recoscen.htm#i1006437

• SIZE OF THE REDO LOG FILE

  
  Hello

  I got an error message when I add me new group. log files I searched and found the answer on the form. Ago 4 M minimum size of 11 g R2 log file size.

  My question is why a log file size depends on DB_BLOCK_SIZE? This parameter is set to the component structures of memory that create an instance when a log file is an operating system file that depend on the version of the OS not DB_BLOCK_SIZE.

  Thank you.

  
  SQL > alter database add logfile group 4 'c:\app\asif\oradata\employee\redo04.log' size 1 m;
  alter database add logfile group 4 'c:\app\asif\oradata\employee\redo04.log' size 1 m
  *
  ERROR on line 1:
  ORA-00336: 2048 blocks the size of the log file is minimum lower than 8192 blocks

  
  SQL > show parameter db_block_size

  VALUE OF TYPE NAME
  ------------------------------------ ----------- ------------------------------
  Whole DB_BLOCK_SIZE 8192
  SQL >

  You are assuming that the redo log block size is the same as the database block size. This is not correct.

  The error indicates that 8192 is the minimum number of blocks of a redo log file. The documentation states that the minimum size is 4 M. For example, you can deduct your redo log block size is 512 bytes.

  Here's some more information about the size of redo log, the documentation block.

  Unlike the database block size, which can always be between 2 K and 32 K, redo log default files to a block size that is equal to the size of physical sector of the disk. Historically, it is usually 512 bytes (512 b).

  Some new large disks offer 4K sizes byte (4K) to increase sector efficiency improved format and ECC capabilities. Most of the Oracle database platforms are able to detect this bigger sector size. The database then automatically creates files redo log with a block size of 4 K of these discs.

• That redo log files waiting?

  Hello Experts,

  I read articles on the log redo and undo segment files. I was wondering something very simple. That redo log files waiting in there? It stores the sql statements?

  Lets say that my update statement to modify 800 blocks of data. A unique single update statement can modify different data 800 right blocks? Yes, it may be true. I think that these data blocks can not hold buffers to the log to roll forward, right? I mean I know exactly what to do redo log buffer and redo log file. And I know that the task of backgrounding LGWR. But, I wonder if she she holds the data blocks? It is not supposed to hold data like cache buffer blocks, right?

  My second question is, rollback isn't effect to restore the newspaper to the right buffer? Because it does not need log buffer for effect do it again. Conversely, the restoration; statement is included in the restore log buffer by progression when someone isse, am I right?

  As far as I know, rollback interact directly with UNDO TABLESPACE?

  I hope that I have to express myself clearly.

  Thanks in advance.

  Here's my question:

  My second question is, rollback isn't effect to restore the newspaper to the right buffer? Because it does not need log buffer for effect do it again. Conversely, the restoration; statement is included in the restore log buffer by progression when someone isse, am I right?

  As far as I know, rollback interact directly with UNDO TABLESPACE?

  Yes, where else would the undo data come from? Undo tablespace contains the Undo segments that contain the Undo data required for the restoration of your transaction.

  I can say that rollback does not alter the data of the log buffer rede to the past. In other words, change vectors will be remain the same before restoration. Conversely, rollback command is also recorded in the log file of restoration by progression. As the name, all orders are saved in the REDO LOGS.

  I hope that I am wrong so far?

  Not sure why you even the buffer log roll forward for Rollback? This is the reason why I asked you it was for, where occurs the dose the cancellation? And the answer for this is that it happens in the buffer cache. Before you worry about the drivers of change, you must understand that it is not serious what contains where as long as there is no transaction recorded in the operating of the Undo segment table. If the operating table indicates that the transaction is longer there, there must be a cancellation of the transaction. Vectors of change are saved in the file log roll forward, while the restore happens on blocks of data stored in the file "data" undo blocks stored in the undo file "data".

  At the same time I read an article about redo and undo. In this article process transaction is explained. Here is the link http://pavandba.files.wordpress.com/2009/11/undo_redo1.pdf

  I found some interesting information in this article as follows.

  It is worth noting that during the restore process, recovery logs never participate. The only time where redo logs are read is retrieving and archiving. This is the concept of tuning key: redo logs are written on. Oracle does not read during normal processing. As long as you have sufficient devices so that when the ARC is reading a file, LGWR's writing to a different device, then there no contention for redo logs.

  If redo logs are never involved in the restoration process, how is it Oracle will then know the order of the transaction? As far as I know it is only written in redo logs.

  I have thoughts very amazed to Aman.

  Why you ask?

  Now, before giving a response, I say two things. One, I know Pavan and he is a regular contributor to this forum and on several other forums Facebook and two, with all due respect to him, a little advice for you, when you try to understand a concept, to stick to the Oracle documentation and do not read and merge articles/blog-posts from the web. Everone, which publishes on the web, has their own way to express things and many times, the context of the writing makes it more confusing things. Maybe we can erase the doubts that you can get after reading the various search results on the web.

  Redo logs used for the restoration, not to restore. The reason is the redo log files are applied in sequential order, and this is not the case when we look for the restoration. A restore is required to do for a few blocks away. Basically, what happens in a restoration, is that the records of cancellation required for a block of data are sought in the reverse order of their creation. The entry of the transaction is in the slot ITL of the block of data that point to the necessary undo bytes Address (UBA) using which oracle also knows what that undo the blocks would be necessary for the restoration of your transaction. As soon as the blocks of data will be cancelled, the ITL slots would be cleared as well.

  In addition, you must remember, until the transaction is not qualified as finished, using either a commit or a rollback, the cancellation of this data would remain intact. The reason for this is that oracle would ensure that undo data would be available to make the cancellation of the transaction. The reason why Undo data are also recorded in the journals of recovery is to ensure that in the event of the loss of the cancellation of the data file, retrieving them would be possible. Because it would also require changes that's happened on the blocks cancel, restore the vectors change associated with blocks of cancellation are also saved in the buffer log roll forward and, in the redo log files.

  HTH

  Aman...

• Separate ASM diskgroup Online redo logs

  Version: 11.2.0.3

  Platform: Solaris 10

  One of the guys support Hitachi suggested to create a group of separate drives for the online redo logs. His reasoning was that ORLs was writing only the files and it would be better to put into a group of separate disk.

  What do you think guys?

  Tom wrote:

  Version: 11.2.0.3

  Platform: Solaris 10

  One of the guys support Hitachi suggested to create a group of separate drives for the online redo logs. His reasoning was that ORLs was writing only the files and it would be better to put into a group of separate disk.

  What do you think guys?

  Well, one additional DG would require additional disks.  Hmm.  And who is the seller who would be purchased these discs?

  I guess that in a situation of extreme performance, there may be some merit in placing redo it online on a separate ASM disk group so that the underlying disks could be managed in a higher priority of the Hitachi (?) SAN.  But that would only be justified if written again online has been the major bottleneck in your system.

• DB restore Archives not lost mode redo log file... restore from controlfile tr

  I have a 11g database I had taken an archive backup but has failed to take redo backup of log files...
  so, while I restored the PB... after formatting the machine... the oracle instance does not start.
  
  
  I create controlfile track but when I run it I get errors.
  given that I don't have the old log files... How can I get around this issue
  Thank you
  Here is the example of trace control file... Note that I can't create the redo log file
  given that the db will not climb up, it must be in mode nonmount
  and here's my created controlfile...
  CREATE CONTROLFILE REUSE DATABASE "XE" NORESETLOGS NOARCHIVELOG
  MAXLOGFILES 16
  MAXLOGMEMBERS 3
  MAXDATAFILES 100
  MAXINSTANCES 8
  MAXLOGHISTORY 292
  LOGFILE
  GROUP 1
  ' C:\ORACLEXE\APP\ORACLE\FLASH_RECOVERY_AREA\XE\ONLINELOG\O1_MF_1_80L7C259_. JOURNAL"
  SIZE 50 M 512 BLOCKSIZE,
  GROUP 2
  ' C:\ORACLEXE\APP\ORACLE\FLASH_RECOVERY_AREA\XE\ONLINELOG\O1_MF_2_80L7C375_. JOURNAL"
  SIZE 50 M BLOCKSIZE 512
  -STANDBY LOGFILE
  DATA FILE
  ' C:\ORACLEXE\APP\ORACLE\ORADATA\XE\SYSTEM. DBF',.
  ' C:\ORACLEXE\APP\ORACLE\ORADATA\XE\UNDOTBS1. DBF',.
  ' C:\ORACLEXE\APP\ORACLE\ORADATA\XE\SYSAUX. DBF',.
  ' C:\ORACLEXE\APP\ORACLE\ORADATA\XE\USERS. DBF'
  CHARACTER SET AL32UTF8
  ;
  
  I do not have these 2 files... what should I do to work around this situation
  ' C:\ORACLEXE\APP\ORACLE\FLASH_RECOVERY_AREA\XE\ONLINELOG\O1_MF_1_80L7C259_. JOURNAL"
  SIZE 50 M 512 BLOCKSIZE,
  GROUP 2
  ' C:\ORACLEXE\APP\ORACLE\FLASH_RECOVERY_AREA\XE\ONLINELOG\O1_MF_2_80L7C375_. JOURNAL"
  SIZE 50 M BLOCKSIZE 512
  -STANDBY LOGFILE
  DATA FILE
  
  Published by: zycoz100 on February 27, 2013 22:57

  If you have a backup to cold (closing correctly database) without the redo logs, change this:

  CREATE CONTROLFILE REUSE DATABASE "XE" NORESETLOGS NOARCHIVELOG
  

  TO

  CREATE CONTROLFILE REUSE DATABASE "XE" RESETLOGS NOARCHIVELOG
  

  You need to change the NORESETLOGS RESETLOGS for Oracle to recreate online redo logs.

  Hemant K Collette

• bottleneck during the passage of the redo log files.

  Hi all
  
  I'm using Oracle 11.2.0.3.
  
  The enforcement team has indicated that they are facing slow at some point.
  
  I followed the database and I found that at some passage of redo log files (not always), I am facing a slow at the application level.
  
  I have 2 son since my database is CARS, each thread has 3 groups of multiplexed redo logs the FIU, with size of 300 MB each.
  
  Is it possible to optimize the switch of the redo log files? knowing that my database is running in ARCHIVELOG mode.
  
  Kind regards

  Hello

  Yes, Oracle recommends 1 validation by 30 calls from users or less. Of course, every database is different, so this rule cannot be taken too literally, but in your case, this rule seems to apply. In any case State, 900 undertakes seconds it looks like a very large number and the need for a high number of transactions should be questioned. You should talk to your analysts/application management/enterprise architect if warranted - that is to say if the application does in fact almost 2 000 business transactions per second.

  What about DB CPU: here is a link to a blog that I wrote on this subject, it should help to better understand this number:

  http://Savvinov.com/2012/04/06/AWR-reports-interpreting-CPU-usage/

  But briefly: DB processor isn't a real event, it is simply an indication that the sessions are on CPU (or waiting for CPU) rather than wait on i/o requests or events in the database. It is not necessarily a bad thing, because the database must perform tasks and he cannot do without loading the CPU. It may indicate a problem in two cases: when the CPU usage is close to the limit of the host (OS stats section indicates that you are very far from there) or when the CPU is a % of DB time - in the latter case, this could mean that you are making too many logical reads due to inefficient plans or analysis too. In any case, this does not apply to you, because 20 percent is not very high a number.

  Other items in the list of the top 5 deserve attention, too - gc buffer busy acquire, gc current block busy, enq: TX - line lock conflict.

  To summarize, your database under a lot of stress - whether it is the legitimate workload, and if this is the case, you may need to upgrade your hardware later. There is chance that it isn't - for example a high number of runs may indicate that rather than to bulk operations database code using PL/SQL loops, which is a big performance killer. Check "Top SQL by executions" about whether or not this is the case.

  Good luck!

  Best regards
  Nikolai

• Online Redo Log

  Hi all
  
  I have a question about the online redo logs.
  If the database is out of service information on recovery online logs will be lost?
  What happens if the entire database server is low because of the blackout? online redo logs is deleted? taking into account the fact that their records were not damaged.
  
  So my question is: the online redo logs fade in all cases? on the database shutdown or restart the database server?
  
  Kind regards

  I have a question about the online redo logs.
  If the database is out of service information on recovery online logs will be lost?

  NO.

  What happens if the entire database server is low because of the blackout? online redo logs is deleted? taking into account the fact that their records were not damaged.
  NO.

  So my question is: the online redo logs fade in all cases? on the database shutdown or restart the database server?

  They fade is an administrator issues the command
  change the database to clear log file group;

  They are your life insurance, so Oracle erase.

  -----------
  Sybrand Bakker
  Senior Oracle DBA

• What is the role of the archived in an incremental backup redo log files?

  I want to know, to which RMAN reads what block of data is changed after the last incremental backup.
  and what is the role of the archived in an incremental backup redo log files?
  
  Please guide.

  Hello

  First Querstion response->
  Each block of data in a data file contains a system change number (SCN), which is the SCN of the last change to the block. During an incremental backup, RMAN reads the RCS of each block of data in the input file and compares at the checkpoint SCN of the incremental backup from parent. If the RCS in the block of input data is greater than or equal to checkpoint SCN of the parent, then RMAN copies the block.

  2 - the archived redolog files are required for the restoration of the online of rman incremental backup in a consistent state.

  Thank you & best regards
  Rahul Sharma

• number of redo log files

  Hello
  What is the best practice to determine the number of redo log files,
  3 groups with 1 member of each or,
  2 groups with 2 members of each?
  which is optimal and recommended?
  Thank you very much

  Agree with Deepak.

  http://download.Oracle.com/docs/CD/B19306_01/server.102/b14231/onlineredo.htm#i1306224

  Read the link. It will help you.

  Concerning
  Asif Kabir

• Clearing Online redo logs on the physical standby of the target

  Hello
  
  Version 11202.
  
  Primer on computer a.
  Watch on computer b.
  
  Later note: 11.2 Data Guard physical standby failover best practices using SQL * Plus [1304939.1 ID].
  

   
  Online redo logs on the target physical standby need to be cleared before that standby database can become a primary database. 

  And later:

   
  On the target physical standby run the following query to determine if the online redo logs have not been cleared... 

  (1) I did not understand where I have to run the query. On computer A, computer B or?
  2)

   
           Online redo logs on the target physical standby need to be CLEARED 
          

  Which means that it must be DELETED? Does transaction could be lost by running the command of compensation?
  
  Thank you

  Hello again;

  I would NOT use a script. The reason is that you are not sure what "switchover_status" will be returned by the database of v$.

  Oracle a broker data available for a quick pass, but I'm from the old school and I want to see how thing works in SQL for awhile first.

  Best regards

  mseberg