Why Redo log files not backup

Hi everyone,
I have a scenario where the my DB is running in archivelog mode and users are making changes to DB as usual, and all of a sudden my db crashes due to some power outage or failed disks or something bad..
Now my DB is inconsistent i can't access my DB due to a failed disk. I need to perform a complete recovery of the database as the database is in archivelog mode I can restore from a previous backup and apply the redo from the archived logfiles. Here comes my doubt what about the current online redologfile that has not been archived and which contain info about the commited transaction. how to recover the db upto the point of failure. help need in this situation..
Edited by: user8710159 on Feb 14, 2010 1:18 PM

user8710159 wrote:
Hi everyone,
I have a scenario where the my DB is running in archivelog mode and users are making changes to DB as usual, and all of a sudden my db crashes due to some power outage or failed disks or something bad..
Now my DB is inconsistent i can't access my DB due to a failed disk. I need to perform a complete recovery of the database as the database is in archivelog mode I can restore from a previous backup and apply the redo from the archived logfiles. Here comes my doubt what about the current online redologfile that has not been archived and which contain info about the commited transaction. how to recover the db upto the point of failure. help need in this situation..
Edited by: user8710159 on Feb 14, 2010 1:18 PMIf you still had a viable copy of the online redo and current control file, the recover would apply them as well. Without them, you'll have to do an incomplete recovery and reset logs.
Which is why you always want to multiplex your control file and online redo - and have the multiplexed copies as physically separate as possible. Those multiplexed copies are your backup for the online redo logs that have not yet been archived.
Edited by: EdStevens on Feb 14, 2010 5:07 PM

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    AVG_IDLE_TIME                             81,268
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    AVG_USER_TIME                             10,548
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    IDLE_TIME                              1,951,741
    IOWAIT_TIME                                  288
    SYS_TIME                                 165,709
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    RSRC_MGR_CPU_WAIT_TIME                         0
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    VM_OUT_BYTES                          75,862,008
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    NUM_CPU_CORES                                  6
    NUM_LCPUS                                     24
    NUM_VCPUS                                      6
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    GLOBAL_SEND_SIZE_MAX                   4,194,304
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  • Backup vs redo log files

    Hi,
    Can anyone tell me what's the real difference between a backup file and a redo log file/archived redo log file and the scenarios (examples) when each of them can be used (for example, "......") ? Both are used for database/instance recovery. I have read the concepts of there 2 terms, but I need some additional information about the difference.
    Thanks!

    Roger25 wrote:
    What i still don't understand is how redo mechanism works; I know, redo logs records changes made to the database and it's used to re-do informations in case of a system failure/crash, for example. Ok, let's say I have a huge update, but when the system crash has occured, the transaction is neither comitted, nor rolled back. Then, how this redo is useful? If a system crash occur, all those updates aren't rolled back automatically? So the database state is as before executing that huge update? So in this case, 'what to redo'?No, with the system's crash, the transaction never gets a chance to get committed (and even rolled back) because a commit is only supposed to happen if there is an explicit or implicit commit statement is issued. Now, for the redo , with the statement, a commit marker is entered at the end of the redo stream of that transaction denoting that it's finally over now and for the corresponding transaction, the status is cleared from the transaction table that's stored in the Undo segment in which the Undo information of that transaction is stored. If you have given a huge update, the redo would be very highly required as you should be knowing that it's not all the time that the dirty buffers that are written to the data files unlikely the redo log files which are written every 3 econds. This means, there is a very fair chance that many changes have yet not even propagated to the data files for which the change vectors are now already there in the redo log files. Now, for the sake of clarity, assume that this transaction was actually committed! So now, without those changes be applied to the data files how Oracle can actually show the committed reults when the database next time would be opened? For this purpose, the redo change vectors are required. And for the uncommitted transactions , the applcation of the redo change vectors would keep on updating the Checkpoint numbers of the data files and would eventually get them synched with the control file and redo log files, without which the database would never be opened.
    HTH
    Aman....

  • Backup of redo log files

    Hello,
    How can I make a backup with redo log files using the following parameters?
    backup_type = online_cons
    backup_dev_type =  disk_copy
    -->archive_function = save_delete (It could be changed. Maybe it is the source of the error)
    The copy is made, but an error occurs when it tries to copy the redo log files. The log shows the following message:
    BR0291I BRARCHIVE will be started with options '-U -d disk_copy -c force -p initFDP_local.sap -cds'
    BR0002I BRARCHIVE 6.40 (43)
    BR0169I Value 'disk_copy' of parameter/option 'backup_dev_type/-d' ignored for 'brarchive' - 'disk'assumed
    BR0181E Option '-cds' not supported for 'disk'
    BR0007I End of offline redo log processing: adxexvpd.log 2008-02-06 03.41.57
    Thanks in advance,
    Ricard.
    Edited by: Oscar Barrabes on Feb 6, 2008 10:08 AM

    Hi Ricard,
    You are right, you need to change the entry
    archive_function = save_delete
    to
    archive_function = save
    in init<SID>.sap
    Nahum

  • Redo log files are not applied in DR of primary

    Hi All,
    I have a DR database of primary on QA Serevr. The Redo log files are not properly applied in the DR database.
    The Oracle version is 11.2.0.1 Some of the files get shipped and applied to DR database automatically but not all.
    SQL> select status, error from v$archive_dest where dest_id=2; gives following massage
    ERROR     ORA-16086: Redo data cannot be written to the standby redo log
    Please suggest.
    Regards,
    Shashi

    Hi,
    Sorry for delay in response. Here I am attaching the error captured in standby database.
    Please advise
    alert_abc.log
    RFS[1780]: Identified database type as 'physical standby': Client is LGWR SYNC pid 21855
    Primary database is in MAXIMUM AVAILABILITY mode
    Standby controlfile consistent with primary
    Standby controlfile consistent with primary
    RFS[1780]: No standby redo logfiles of file size 94371840 AND block size 512 exist
    Clearing online log 16 of thread 0 sequence number 0
    Errors in file /oracle/diag/rdbms/abc_location11/abc/trace/abc_rfs_27994.trc:
    ORA-00367: checksum error in log file header
    ORA-00315: log 16 of thread 0, wrong thread # 1 in header
    ORA-00312: online log 16 thread 0: '/oracle/abc/origlogB/log_g116m1.dbf'
    Mon Nov 14 00:49:16 2011
    Clearing online log 9 of thread 0 sequence number 0
    Errors in file /oracle/diag/rdbms/abc_location11/abc/trace/abc_arc0_15653.trc:
    /oracle/diag/rdbms/abc_location11/abc/trace/abc_rfs_27994.trc
    2011-11-14 00:49:19.385
    DDE rules only execution for: ORA 312
    START Event Driven Actions Dump -
    END Event Driven Actions Dump -
    START DDE Actions Dump -
    Executing SYNC actions
    START DDE Action: 'DB_STRUCTURE_INTEGRITY_CHECK' (Async) -
    DDE Action 'DB_STRUCTURE_INTEGRITY_CHECK' was flood controlled
    END DDE Action: 'DB_STRUCTURE_INTEGRITY_CHECK' (FLOOD CONTROLLED, 1 csec) -
    Executing ASYNC actions
    END DDE Actions Dump (total 0 csec) -
    ORA-00367: checksum error in log file header
    ORA-00315: log 16 of thread 0, wrong thread # 1 in header
    ORA-00312: online log 16 thread 0: '/oracle/abc/origlogB/log_g116m1.dbf'
    DDE rules only execution for: ORA 312
    START Event Driven Actions Dump -
    END Event Driven Actions Dump -
    START DDE Actions Dump -
    Executing SYNC actions
    START DDE Action: 'DB_STRUCTURE_INTEGRITY_CHECK' (Async) -
    DDE Action 'DB_STRUCTURE_INTEGRITY_CHECK' was flood controlled
    END DDE Action: 'DB_STRUCTURE_INTEGRITY_CHECK' (FLOOD CONTROLLED, -641 csec) -
    Executing ASYNC actions
    END DDE Actions Dump (total 0 csec) -
    ORA-19527: physical standby redo log must be renamed
    ORA-00312: online log 16 thread 0: '/oracle/abc/origlogB/log_g116m1.dbf'
    Error 19527 clearing SRL 16
    /oracle/diag/rdbms/abc_location11/abc/trace/abc_arc0_15653.trc
    ORA-19527: physical standby redo log must be renamed
    ORA-00312: online log 9 thread 0: '/oracle/abc/origlogA/log_g19m1.dbf'
    Error 19527 clearing SRL 9
    DDE rules only execution for: ORA 312
    START Event Driven Actions Dump -
    END Event Driven Actions Dump -
    START DDE Actions Dump -
    Executing SYNC actions

  • Private strand flush not complete how to find optimal size of redo log file

    hi,
    i am using oracle 10.2.0 on unix system and getting Private strand flush not complete in the alert log file. i know this is due to check point is not completed.
    I need to increase the size of redo log files or add new group to the database. i have log file switch (checkpoint incomplete) in the top 5 wait event.
    i can't change any parameter of database. i have three redo log group and log files are of 250MB size. i want to know the suitable size to avoid problem.
    select * from v$instance_recovery;
    RECOVERY_ESTIMATED_IOS     ACTUAL_REDO_BLKS     TARGET_REDO_BLKS     LOG_FILE_SIZE_REDO_BLKS     LOG_CHKPT_TIMEOUT_REDO_BLKS     LOG_CHKPT_INTERVAL_REDO_BLKS     FAST_START_IO_TARGET_REDO_BLKS     TARGET_MTTR     ESTIMATED_MTTR     CKPT_BLOCK_WRITES     OPTIMAL_LOGFILE_SIZE     ESTD_CLUSTER_AVAILABLE_TIME     WRITES_MTTR     WRITES_LOGFILE_SIZE     WRITES_LOG_CHECKPOINT_SETTINGS     WRITES_OTHER_SETTINGS     WRITES_AUTOTUNE     WRITES_FULL_THREAD_CKPT
    625     9286     9999     921600          9999          0     9     112166207               0     0     219270206     0     3331591     5707793please suggest me or tell me the way how to find out suitable size to avoid problem.
    thanks
    umesh

    How often should a database archive its logs
    Re: Redo log size increase and performance
    Please read the above thread and great replies by HJR sir. I think if you wish to get concept knowledge, you should add in your notes.
    "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
    Pl also see ML Doc 274264.1 (REDO LOGS SIZING ADVISORY) on tips to calculate the optimal size for redo logs in 10g databases
    Source:Re: Redo Log Size in R12
    HTH
    Girish Sharma

  • Database in log archive mode and redo log file in mode not archive

    Hello,
    I have a dabatabase running in archive log mode, recently changed, I have 5 redo log groups and one of them (the current one) shows in the v$log view, that ARC: NO, I mean, no archiving. All redo logs except it shows ARC:Yes
    What does it mean?
    Am I going to have problems with this redo log file?
    Thanks

    If you do describe on v$log, you'll find that the full column name is Archived (meaning is it archived yet?).
    You could try alter system switch logfile and then check v$log again a few times after.
    Use the docu for finding out more about v$ views and so on
    http://www.oracle.com/pls/db102/print_hit_summary?search_string=v%24log

  • Moving ORACLE_HOME , Datafiles, controlfiles,redo log file locations

    Version: 10.2.0.1.0
    One of our test DB's software location(ORACLE_HOME) was wrongly installed in /home/oracle. We have been using this for an year now. Now we are thinking of moving the ORACLE_HOME to a new location /u02. Because of another disk maintenance activity, we have to move all datafiles , redo log files, control files, tempfiles to a different location as well.
    This database is not in ARCHIVELOG mode(luckily).
    If i do a fresh installation of 10.2.0.1.0 in /u02, i cannot use the old installation's system01.dbf, sysaux01.dbf,undotbs01.dbf files for this fresh installation. Right?
    How do i go about doing this whole move thing?

    This database is not in ARCHIVELOG mode(luckily).
    Why?
    If i do a fresh installation of 10.2.0.1.0 in /u02, i cannot use the old installation's system01.dbf, sysaux01.dbf,undotbs01.dbf files for this fresh installation. Right?
    No.
    Issue ALTER DATABASE BACKUP CONTROLFILE TO TRACE. Then Shutdown the database. Copy all the files including the trace generated. Change the control_files parameter from init<SID>.ora file. Copy this to new home. Also tailor the backup trace file for change in location of logfiles,datafiles. Then
    $export ORACLE_SID=<SID>
    $sqlplus /nolog
    SQL>conn sys as sysdba
    password:<Enter>
    SQL>startup nomount pfile=NEW_HOME/dbs/init<SID>.ora
    SQL>@location_of_trace_file_generated/tracefilename.trc
    Add temporary tablespace and make it default temporary tablespace for the database.
    Your database will be up and running.
    Regards.
    Edited by: orant575 on Jul 10, 2009 4:37 PM

  • How to disable write to redo log file in oracle7.3.4

    in oracle 8, alter table no logged in redo log file like: alter table tablename nologging;
    how to do this in oracle 7.3.4?
    thanks.

    user652965 wrote:
    Thanks very much for your help guys. I appreciate it. unfortunately none of these commands worked for me. I kept getting error on clearing logs that redo log is needed to perform recovery so it can't be cleared. So I ended up restoring from earlier snapshot of my db volume. Database is now open.
    Thanks again for your input.And now, as a follow-up, at a minimum you should make sure that all redo log groups have at least 3 members. Then, if you lose a single redo log file, all you have to do is shutdown the db and copy one of the good members (of the same group as the lost member) over the lost member.
    And as an additional follow-up, if you value your data you will run in archivelog mode and take regular backups of the database and archivelogs. If you fail to do this you are saying that your data is not worth saving.

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