Recreate the Member lost/damaged redo log in a group

Similar Questions

• 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

• How to find the configuration state of REDO logs files?

  I'm trying to move the redo log files.
  Before that, I want to know if it is set as a duplex or any other configuration.
  
  How to find the REDO log configurations.
  
  Oracle 10g R2
  
  Thank you
  Smith

  Example:

  Not in duplex redo log - if the number of members is 1, it is not duplex:

  SQL> select group#, members from v$log;
  
      GROUP#    MEMBERS
  ---------- ----------
           1          1
           2          1
           3          1
  
  SQL> select group#, member from v$logfile;
  
      GROUP# MEMBER
  ---------- --------------------------------------------------
           1 /u01/app/oracle/oradata/db1/redo01.log
           2 /u01/app/oracle/oradata/db1/redo02.log
           3 /u01/app/oracle/oradata/db1/redo03.log
  
  SQL> alter database add logfile member '/u01/app/oracle/oradata/db1/redo01_2.log' to group 1;
  
  Database altered.
  
  SQL> alter database add logfile member '/u01/app/oracle/oradata/db1/redo02_2.log' to group 2;
  
  Database altered.
  
  SQL> alter database add logfile member '/u01/app/oracle/oradata/db1/redo03_2.log' to group 3;
  
  Database altered.
  

  Duplex redolog

  SQL> select group#, members from v$log;
  
      GROUP#    MEMBERS
  ---------- ----------
           1          2
           2          2
           3          2
  
  SQL> select group#, member from v$logfile;
  
      GROUP# MEMBER
  ---------- --------------------------------------------------
           1 /u01/app/oracle/oradata/db1/redo01.log
           2 /u01/app/oracle/oradata/db1/redo02.log
           3 /u01/app/oracle/oradata/db1/redo03.log
           1 /u01/app/oracle/oradata/db1/redo01_2.log
           2 /u01/app/oracle/oradata/db1/redo02_2.log
           3 /u01/app/oracle/oradata/db1/redo03_2.log
  

• Get the former locations of the data files and Redo logs

  Version: 11.2
  Platform: Solaris 10
  
  When we manage hundreds of DBs, we do not know the locations of all DB files these allows DBs. say a DB goes down and you have all the required RMAN backups.
  
  When you restore the DB in a new location in the path of the new server, you must run the commands for the data files and ORLs below. But how do we know
  
  The former location of the data files.
  
  B. the old location of redo online stores that I can run
  
  run

  alter database rename file 'oldPath_of_OnlineRedoLogs' to 'newPath_of_OnlineRedoLogs' ;  --- Without this command , the restored control file will still reflect the old control file location

  run {
  set newname for datafile 1 to '/u04/oradata/lmnprod/lmnprod_system01.dbf' ;
  set newname for datafile 2 to '/u04/oradata/lmnprod/lmnprod_sysaux01.dbf' ;
  set newname for datafile 3 to '/u04/oradata/lmnprod/lmnprod_undotbs101.dbf' ;
  set newname for datafile 4 to '/u04/oradata/lmnprod/lmnprod_audit_ts01.dbf' ;
  set newname for datafile 5 to '/u04/oradata/lmnprod/lmnprod_quest_ts01.dbf' ;
  set newname for datafile 6 to '/u04/oradata/lmnprod/lmnprod_yelxr_ts01.dbf' ;
  .
  .
  .
  .
  .
  }

  Hello

  With the help of Oracle 11.2, you can use feature 'set newname for database' using OMF.

  SET NEWNAME FOR DATABASE TO '/oradata/%U';
  RESTORE DATABASE;
  SWITCH DATAFILE ALL;
  SWITCH TEMPFILE ALL;
  RECOVER DATABASE;
  

  After the restore and recover databases (i.e. before resetlog open) you can do to rename redolog. Just a query column member from v$ logfile and deliver ' alter database rename file 'oldPath_of_OnlineRedoLogs' to 'newPath_of_OnlineRedoLogs ';

  When we use the DSO is much easier to use OMF because Oracle automatically creates the directory structure.
  But when we use the file system that the OMF does not serve due DBA dislikes system generated on file system names.

  If you don't like OMF file system, you can use the script on thread below to help restore you using readable for datafile names, tempfile, and redo.

  {message: id = 9866752}

  Kind regards
  Levi Pereira

• Redo log and members groups

  Hi I got very confused by looking at the documentation of redo log groups and members of 11g.
  
  Please could someone help me with that?
  
  -What is the difference between a group of newspapers of restoration by progress and members within the Group?
  
  -How does add a member help protect / multiplex a group?
  
  -I am course I've read that if all members of the current redo log group are damaged, then 2 other groups does not bring the database back to how it was? ... so what's the point of having them?
  
  Any help would be appreciated

  806595 wrote:
  OK thanks, so again an allows for example, we had only one newspaper group and the database was NOT in archivelog mode, once the newspaper filled redo id, it would be re-written and proevious changes would be lost?

  Before you start, don't forget not that whenever you would need redolog groups, this will be the mandatory requirement, 2:1, and that means that 2 groups of newspaper with 1 member of each. Now, the newspaper group is a logic thing. There is no such thing actually exists. His way to the club/join/merge/combine/group multiple and physics redo log files that are written together. A minimum of a physical member is a must in a group, therefore 2:1.

  Now, groups of newspapers (and in their midst, the log files are in fact) are written sequentially by LGWR, which means that LGWR would write about a group and all its members at the same time, fill it out completely and then made a switch (called a LOG SWITCH) to the next group of inactive log and keeps current processes. This is why a minimum of paper two groups are needed for the LGWR to work. The ius of work done on a single group and when the switch happens, work of the previous, filled will be controlled for the data files and will be marked as inactive thereafter, which makes even elgible for the LGWR to write to.

  HTH
  Aman...

• Loss/Corruption of a Redo Log multiplex group member

  Grid infrastructure: 11.2.0.4

  DB version: 11.2.0.4

  OS: RHEL 6.5

  All recovery logs are multiplexed IE once. Copy of a mirror

  I created a document on how to cope with the loss of a member of a group of Redo Log multiplex. It applies to DBs in ASM or Linux Filesystem.

  If a member of a multiplex redo logs group is lost/damaged is in State assets or CURRENT (v$ log.status), will be the following work?

  Assuming that the DB would not crash (well that's the whole point of multiplexing)

  Step 1. Switch redo log group and bring him to the INACTIVE State IE. LGWR is not written for her now

  
  

  Step 2. Remove the Member lost/damaged.

  ALTER DATABASE DROP LOGFILE MEMBER "+ DATA_DG1/mbhsprd/onlinelog/group_1.256.834497203";

  Apparently, this command does not actually remove the log file at the level of the ASM/OS; It updates only the control file

  Step 3. If it is a corrupt then log file physically remove the damaged location ASM/OS file

  Step 4. I hope the below will create a mirror copy of the survivor

  ALTER DATABASE ADD LOGFILE MEMBER '+ DATA_DG1/mbhsprd/onlinelog/group_1.256.834497203' to GROUP 3.

  The above steps won't work?

  There is no point in writing in the document if you do not actually test what you write

  It seems that you are working with Oracle managed files. In this case:

  You will find that your "apparently" in step 2 is not correct, and that your step 4 will throw an ora-01276.

• Question about the size of the redo log buffer

  Hello
  
  I am a student in Oracle and the book I use says that having a bigger than the buffer log by default, the size is a bad idea.
  
  It sets out the reasons for this are:
  
  >
  The problem is that when a statement COMMIT is issued, part of the batch validation means to write the contents of the buffer log for redo log to disk files. This entry occurs in real time, and if it is in progress, the session that issued the VALIDATION will be suspended.
  >
  
  I understand that if the redo log buffer is too large, memory is lost and in some cases could result in disk i/o.
  
  What I'm not clear on is, the book makes it sound as if a log buffer would cause additional or IO work. I would have thought that the amount of work or IO would be substantially the same (if not identical) because writing the buffer log for redo log files is based on the postings show and not the size of the buffer itself (or its satiety).
  
  Description of the book is misleading, or did I miss something important to have a larger than necessary log buffer?
  
  Thank you for your help,
  
  John.
  
  Published by: 440bx - 11 GR 2 on August 1st, 2010 09:05 - edited for formatting of the citation

  A commit evacuates everything that in the buffer redolog for redo log files.
  A redo log buffer contains the modified data.
  But this is not just commit who empty the redolog buffer to restore the log files.
  LGWR active every time that:
  (1) a validation occurs
  (2) when the redo log is 1/3 full
  (3) every 3 seconds
  It is not always necessary that this redolog file will contain validated data.
  If there is no commit after 3 seconds, redologfile would be bound to contain uncommitted data.

  Best,
  Wissem

• 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.

• Questions about the parameters of database using a fast recovery area and the writing of two copies of archived redo logs.

  My databases are 11.2.0.3.7 Enterprise Edition. My OS is AIX 7.1.

  I am to convert databases to use individual zones of rapid recovery and have two questions about what values to assign to database settings related to archived redo logs. This example refers to a database.

  I read that if I specify

  Log_archive_dest_1 =' LOCATION = USE_DB_RECOVERY_FILE_DEST'

  the names of newspapers archived redo written in the default quick recovery area is '% t_%S_%r.dbf '.

  In the past my archived redo logs have been appointed based on the parameter

  log_archive_format='GPAIDT_archive_log_%t_%s_%r.arc'

  I think log_archive_format will be ignored for logs archived redo written in the fast recovery area.

  I am planning to write a second copy of the archived redo logs based on the parameter

  ALTER system set log_archive_dest_2 = ' LOCATION = / t07/admin/GPAIDT/arch.

  If I do this, the copy of logs placed in /t07 will be called '% t_%S_%r.dbf' or 'GPAIDT_archive_log_%t_%s_%r.arc '?

  Before my use of a fast recovery area, I used the OEM 12 c Console to specify settings of backup of database that has been deleted and archived redo logs after 1 backup. Oracle manuals say rather specify a deletion of "none" policy and allow Oracle delete newspapers in the area of fast recovery if necessary. Since I got to keep a second copy of these log files in /t07 should I keep the policy that says to delete logs after 1 backup? If I don't do that, how will they removed from /t07?

  Thank you

  Bill

  If I do this, the copy of logs placed in /t07 will be called '% t_%S_%r.dbf' or 'GPAIDT_archive_log_%t_%s_%r.arc '?

  They will be "GPAIDT_archive_log_%t_%s_%r.arc". LOG_ARCHIVE_FORMAT is only ignored for directories under OMF.

  Since I got to keep a second copy of these log files in /t07 should I keep the policy that says to delete logs after 1 backup? If I don't do that, how will they removed from /t07?

  You can hold the deletion policy as it is. Oracle documentation, defining the STRATEGY of the ARCHIVELOG DELETION: "the deletion of archived newspaper policy applies to logs archive destinations, including the area of fast recovery."

• Question about how Oracle manages the Redo logs

  Hello
  
  Assuming a configuration which consists of 2 redo log groups (groups A and B), each group of 2 disks (disks A1 and A2 for Group A) and B1 and B2 disks for Group B. Additionally, assume that each redo log file resides by itself in a disk storage device and that the device is dedicated to her. So in the situation described above, there are 4 discs, one for each redo log file, and each disc contains nothing other than a redo log file. Also, assume that the database is in ARCHIVELOG mode and the files from archive is stored on another different set of devices.
  
  kind of graphically:
  

      GROUP A             GROUP B
  
        A1                  B1
        A2                  B2

  The question is: when the disks that make up the Group A are filled and Oracle switches to the disks in the Group B, can the group drives to take offline, perhaps even physically removed from the system if necessary without affecting the functioning of the database? Can the archiver process temporarily delayed until the disks (which have been removed) are presented online or is the DBA have to wait until the end of the process to archive a copy of the redo log file creating in archive?
  
  Thank you for your help,
  
  John.

  Hello
  A journal of the groups fall

  To remove a group of online redo logs, you must have the ALTER DATABASE system privilege. Before you delete a line redo log group, consider the following precautions and restrictions:

  * An instance requires at least two groups of files logging online, regardless of the number of members in the groups. (A group is one or more members.)
  * You can delete a group of newspapers online redo only if it is inactive. If you need to drop the current group, first force a log switch occurs.
  * Make sure a group of online redo logs is archived (if archiving is enabled) before dropping. To see if this happens, use the view LOG V$.

  SELECT GROUP #, ARCHIVED, STATUS FROM V$ LOG;

  GROUP # ARC STATUS
  --------- --- ----------------
  1 ACTIVE YES
  2. NO CURRENT
  3 INACTIVE YES
  4 INACTIVE YES

  Delete a group of newspapers online redo with the SQL ALTER DATABASE statement with the DROP LOGFILE clause.

  The following statement drops redo log group number 3:

  ALTER DATABASE, DROP LOGFILE GROUP 3;

  When a group of online redo logs is deleted from the database, and you do not use Oracle managed files, operating system files are not removed from the disk. Instead, control of the associated database files are updated to remove members of the Group of the database structure. After deleting a group of online redo logs, make sure the drop completed successfully and then use the command of operating system appropriate to delete the dropped online redo log files.

  When you work with files managed by Oracle, the cleaning of operating system files is done automatically for you.
  Your database will not be affected as you can work with 2 files, redo log in each group, as the minimum number of redo log in a database file is two because the process LGWR (newspaper writer) writes in the redo log in a circular way. If the process crashes because you have 2 groups only if you want to remove 1 Add a third and make that the current group and remove the one you want to be offline.

  Please refer to:
  http://download.Oracle.com/docs/CD/B10500_01/server.920/a96521/onlineredo.htm#7438
  Kind regards
  Mohamed
  Oracle DBA

• 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

• 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

• 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

• Redo Logs

  Running Oracle 11 g r2.

  I just want to confirm if Oracle recommends at least 3 redo logs to run the database?

  If so, how can I create the third (and fourth) redo logs (I believe the default is 2 recovery logs)?

  Thank you.

  Scott

  Running Oracle 11 g r2.

  I just want to confirm if Oracle recommends at least 3 redo logs to run the database?

  Post a link to the source of this information.

  If so, how can I create the third (and fourth) redo logs (I believe the default is 2 recovery logs)?

  You CAN'T do that. Do NOT modify Oracle based on your personal beliefs. You must use FACTS.

  What you believe has NOTHING to do with the reality of what can be your real system. You can only change your system.

  So first, you must determine how many newspaper groups and members your system log has already.

  The detail on the REDO log and groups members that exist on your system. The Oracle documentation at the address provided already has examples on how to do it.

• 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...