Recoevery in Archive Log Mode

If our database is running in Archivelog mode and if instance crashes, then how we can oerfrom the recoevery process in order to recover the lost transactions which were never committed.

The crash recovery process is a special form of recovery, which happens the first time an Oracle database instance is started after a crash (or SHUTDOWN ABORT). In crash recovery, the goal is to bring the datafiles to a transaction-consistent state, preserving all committed changes up to the point when the instance failed.
Unlike the forms of recovery performed manually after a data loss, crash recovery uses only the online redo log files and current online datafiles, as left on disk after the instance failure. Archived logs are never used during crash recovery, and datafiles are never restored from backup.
The database applies any pending updates in the online redo logs to the online datafiles of your database. The result is that, whenever the database is restarted after a crash, the datafiles reflect all committed changes up to the moment when the failure occurred. (After the database opens, any changes that were part of uncommitted transactions at the time of the crash are rolled back.)
Instance Recovery is only used in a RAC environment. It is the application of online redo log by one instance that detected the crash of another instance.

Similar Messages

  • Standby Database (Archive Log Mode)

    I'm going to be setting up a standby database.
    I understand that the primary database must be in archive log mode.
    Is there any reason for the standby database to be in archivelog mode?

    Since your primary Db is in archive log mode, so will be your standby, when it is made primary.But. you can use STANDBY REDO LOGS from 9i version, where these Standby Redo Logs then store the information received from the Primary Database.
    As per metalink:-
    Standby Redo Logs are only supported for the Physical Standby Database in Oracle 9i and as well for Logical Standby Databases in 10g. Standby Redo Logs are only used if you have the LGWR activated for archival to the Remote Standby Database.If you have Standby Redo Logs, the RFS process will write into the Standby RedoLog as mentioned above and when a log switch occurs, the Archiver Process of the Standby Database will archive this Standby Redo Log to an Archived Redo Log, while the MRP process applies the information to the Standby Database. In a Failover situation, you will also have access to the information already written in the Standby Redo Logs, so the information will not be lost.
    Check metalink Doc ID: Note:219344.1

  • Is the only way to import large amount of data and database objects into a primary database is to shutdown the standby, turn off archive log mode, do the import, then rebuild the standby?

    I have a primary database that need to import large amount of data and database objects. 1.) Do I shutdown the standby? 2.) Turn off archive log mode? 3.) Perform the import? 4.) Rebuild the standby? or is there a better way or best practice?

    Instead of rebuilding the (whole) standby, you take an incremental (from SCN) backup from the Primary and restore it on the Standby.  That way, if, for example
    a. Only two out of 12 tablespaces are affected by the import, the incremental backup would effectively be only the blocks changed in those two tablespaces (and some other changes in system and undo) {provided that there are no other changes in the other ten tablespaces}
    b. if the size of the import is only 15% of the database, the incremental backup to restore to the standby is small
    Hemant K Chitale

  • Question about import in archive log mode

    I am a developer, I have ordered to write a script that makes the import of a schema of a database (release That import will be done once a day. I have seen that in my development environment the import creates 54 archivers files (10M aprox. each), that means more that half a Gb a day, it seems too much to me.
    I cannot see why all those archivers can be useful. Would a good way of proceeding the following?
    1. Forcing an archiver just before the import (I do not know how to do that) so that a backup could be done to the state before the import.
    2. Disabling archive log mode during the import and enabling it just after the import (I do not know how to do that).
    3. Forcing a new archiver just after the import (I do not know how to do that).
    Thanks in advance.

    540M is not that much.
    One would question why you need to import every day,
    there must be better ways to do this.
    The three steps you propose look like an awful
    scenario, as it would require the database to switch
    from archivelog to noarchivelog and vice versa.
    This would require the database to close twice a
    The scenario is also incomplete as one would need to
    take a backup after the import
    If you can convince your DBA to close the database
    twice a day, he should write the script, which he can
    easily derive from the docs.
    But likely he will visit Billy Verreynne to borrow
    his lead pipe, and rightly so ;)
    Sybrand Bakker
    Senior Oracle DBAThanks for the answer.
    A few things:
    - Sorry for my ignorance, I have no experience in database backups, I do not understand why I need to backup just after the import.
    - That database is not critical, it is just for a team who will test on that database several applications, so the database will only need to be open during the office schedule.
    - I have no dba. The client has a dba for several databases but I have no contact with him/her nor my boss has.

  • Archive log mode in oracle 10g

    I would like to know the archive log mode in oracle 10g and I use this code in SQLPlus
    select log_mode from v$database
    But it displayed: "2" not : NOARCHIVELOG or ARCHIVELOG
    It displayed a number, not a String.
    How could I know this?

    Hi Paul
    Because I am a newbie in DBA Oracle so I got many difficulties.
    You are very kind to help me.
    So I have some more questions:
    1. when I executed this code, it always reported error:
    $ tmp=`${ORACLE_HOME}/bin/sqlplus -s / as sysdba << EOF
    set heading off feedback off;
    ORA-01031: insufficient privileges
    SP2-0306: Invalid option.
    Usage: CONN[ECT] [logon] [AS {SYSDBA|SYSOPER}]
    where <logon> ::= <username>[<password>][@<connect_identifier>] | /
    SP2-0306: Invalid option.
    Usage: CONN[ECT] [logon] [AS {SYSDBA|SYSOPER}]
    where <logon> ::= <username>[<password>][@<connect_identifier>] | /
    SP2-0157: unable to CONNECT to ORACLE after 3 attempts, exiting SQL*Plus'
    so when I updated like this:
    tmp=`${ORACLE_HOME}/bin/sqlplus -s sys/[email protected] as sysdba <<EOF     
                   set heading off feedback off;
    It run correctly.
    2. With Paul's guide:
    Do not execute Oracle commands from root, execute them as oracle user. This works to me :
    $ tmp=`${ORACLE_HOME}/bin/sqlplus -s / as sysdba << EOF
    set heading off feedback off
    alter database backup controlfile to '${CONTROLFILE_DIR}/<file name>';
    alter database backup controlfile to trace;
    Of course CONTROLFILE_DIR must be set to a directory with write permission for oracle user.
    For ex: I have an Unix account: unix/unix
    and a Sys Oracle account: oracle/oracle
    I login with Unix acount (unix/unix) and call script file that contains above code.
    tmp=`${ORACLE_HOME}/bin/sqlplus -s oracle/[email protected] as sysdba <<EOF     
                   set heading off feedback off
                   alter database backup controlfile to '${CONTROLFILE_DIR}/backup_control.ctl';
                   alter database backup controlfile to trace;
    Unix report as following: Linux error: 13: Permission denied.
    CONTROLFILE_DIR directory is read,write,execute for account unix/unix.
    Of course CONTROLFILE_DIR must be set to a directory with write permission for oracle user. You mean I have to create a Unix user is the same to Oracle user so that Oracle user can have permission to write.
    Please guilde more detail.
    Thanks for your attention.
    Message was edited by:

  • Disabling Log_Archive_Start in Archive Log Mode

    I have a Database running in Archive Log mode.
    I have a situation where in I have to do bunch of bulk updates for which I dont want any logs generated.
    sO I was thinking to set the intialization parameter log_archive_start to false before I run the DML updates
    ALTER SYSTEM SET log_archive_start = false
    after the DML is run I will turn it back on
    ALTER SYSTEM SET log_archive_start = True
    Do you think if this is the right to go about or would I have to switch from Archive Log Mode to No Archive Log Mode
    run the DML update and then switch back to Archive Log Mode
    Any comments/suggestions/inputs woo

    I would use some other way to get a full nologing behaviour.
    First, ensure your tablespace is in force logging mode.
    This will ensure that you're usually logging.
    Set all tables/indexes to be nologging
    Do even for indexes.
    From now on, when you want to do your huge amount of updates/... targetting objects in tablespaces data and index, jou just have to:
    - Your DML
    4 commands to disable logging for every object in the tablespace.
    Beware, when in NOLOGGING mode, you won't be able to "RECOVER" any of the tables. Thiis is not crash-friendly, but you'll have no redo info generated, which is what you require.

  • Physical standby in archive log mode

    HI ,
    Our phyiscal standby database is running in archive log mode,
    1.Is it manadatory to have it in archive log mode ?
    2.As it is in archive log mode , does it produce any archivelog ?

    Hello again;
    The Standby is a clone of the Primary. I assume we are talking Physical Standby.
    Why does it need to produce archive in standby role?Its does not produce archive in the Standby role. I have seen a Standby produce a log now and then, but not log after log like a primary. A Standby database does not write Redo or use Redo logs, it uses Standby Redo logs. Since Redo logs are not used, archive is not written.
    Why it is manadatory to enable archive log in standby?Smart design I'm thinking. Why would Oracle make us add this complex step to a failover/switchover?
    Keep it simple if possible.
    Data Guard Concepts and Administration 11g Release 2 (11.2) E10700-02
    Database Concepts
    Best Regards

  • Archive log mode

    i m using oracle 10gR2 after installation i enable the archive log mode.
    1) How can i determine the size of archive log?
    2)When i enable the archive log mode after switch it genrate the second archive (01_MF_1_2_43.ARC) instead of first (01_MF_1_1_43.ARC) why?

    The size of archived logs will normally be the same as the size of online redo logs. However, if you switch the logs before the get filled with redo, the size of archived log will be smaller depending in the amount of redo.

  • Archive log mode Turn off

    Hi all DBA guys, Have a Nice day all
    If i change archive log mode to no archive log mode, internally whats happen my database?.
    Is this old archive log backup use for future if again convert no archive to archive log mode?
    What's happen flashback if i change archive log mode to no archive log mode?

    azarmohds wrote:
    Thanx lot,
    why i asked this question means, rightnow you posted, this is feature of 10g i.e flashback database confiured when archive log mode is enabled...,so in this case
    What's happen flashback if i change archive log mode to no archive log mode?S.Azar,
    You should be clear about things that when you read notes from web, there can be a language mismatch. So the best is that search first over the oracle docs.
    Now about your doubt, its a terminology mismatch which is happening here. To enable Flashback Database feature which is more persistent copy of the undo data , stored seperately in a FLB file, you MUST have to have archivelog mode configured in your db. Without this, you can't enable the Flashback Database feature. And you can't switch to noarchive log mode as well if you have Flashback Database mode on.
    The other thing ( which I guess Anurag was mentioning ) is the normal Flashback feature which relies on Undo data stored in the undo tablespace. This solely is based on teh undo data and doesn't depend on the archive/nonarchive log mode of the database. But this is limited to that data and to that time period up till which you can store the undo data in your undo tablespace.

  • Archive log mode doubt

    Hi All,
    We have 10g R2 database running on RHEL 4 OS. In order to set the archive log mode for the database, if we set only log_archive_dest_n parameter is only enough or we have to set db_recovery_file_dest_size and db_recovery_file_dest also? i know that these 2 parameters are required to configure the flash_recovery_area. my doubt is whether, do we need to set flash_recovery_area parameters and log_archive_dest_n parameters to take backup of databases or set only the log_archive_dest_n parameter and enable archive log mode and take backup using RMAN?

    To use RMAN to take a hot backup you need only set LOG_ARCHIVE_DEST_n and place the database in archive log mode. RMAN can be used to backup changed data even after a nologging operation, and you can move away from archivelog mode.
    There is also the new "block change tracking" B&R that does not need archivelog mode:

  • Archive log mode  in 3 node rac database

    Sir I am using oracle and created 3 node cluster setup on.OS i am using linux 4
    I am too much confuse in setting up this cluster in archive log mode bec why we need to false cluater_database parameter to setup cluster in archive log mode.
    I have search lot of documents but all are saying we not need setting this parameter flase perior to 10.2.But what is the actual concept behind setting this parameter to false in early release and why we need not to set it false.Please help me.
    I know how to set up in archive log mode but this parameter create confusion.
    Thanks sir in advance

    I also dont't know all the details about this but I'll try to explain what I know. Setting cluster_database to false in a rac environment is usually done when you need to mount the database from one instance exclusively. This is still needed when you upgrade the catalog, for example during release update (from to for example). Now with switching archivelog mode someone at oracle must have discovered that it is sufficient when the database is mounted by only one instance and you can actually save one step.
    As I (and propably most of you) don't switch archiving on or off on a daily basis, I don't worry about this a lot, simply turn this on when I create a new database and then leave it on forever.

  • SGEN & database archive log mode

    Hi Experts,
    To apply ABAP support packs, I disabled archive log mode of databse and successfully applied support packs.
    As post processing, I kicked off SGEN.
    Is it required that database be in "NO Archive log mode"  while SGEN is running or can I enable it.

    Not sure what database it is.. but if it is ORACLE...
    $sqlplus / as sysdba
    SQL> shutdown immediate;
    SQL> startup mount;
    SQL> Alter database noarchivelog;
    SQL> alter database open;
    After the completion of SGEN.....
    $sqlplus / as sysdba
    SQL> shutdown immediate;
    SQL> alter database mount;
    SQL> alter database archivelog;
    SQL> alter database open;

  • Archive log mode required for async. CDC?

    Hello there,
    I have tried to set up asyn. HotLog CDC on my 10g database but after creating a publisher I get the following error Message when creating a change set with the publisher:
    change_set_name => 'MY_CHANGESET',
    description => 'First Change set',
    change_source_name => 'HOTLOG_SOURCE',
    stop_on_ddl => 'y',
    begin_date => sysdate,
    end_date => sysdate+20);
    following Error-Message:
    ERROR at line 1:
    ORA-00258: manual archiving in NOARCHIVELOG mode must identify log
    ORA-06512: at "SYS.DBMS_CAPTURE_ADM_INTERNAL", line 115
    ORA-06512: at line 1
    ORA-06512: at "SYS.DBMS_CDC_PUBLISH", line 57
    ORA-06512: at line 2
    Does this mean that I have to activate the ARCHIVE LOG-mode, and if yes, how do I do this with the Enterprise Manager?
    I already set the LOG_ARCHIVE_START initparam to "true".

    To place a database in archivelog mode you must:
    Be sure that the log_archive_start and log_archive_dest
    parameters are set in the init file.
    Shut the instance down.
    startup mount;
    alter database archivelog;
    alter database open;

  • When creating a tablespace why should we enable LOGGING when a database is already on ARCHIVE LOG mode

    Question :
    When creating a tablespace why should we enable LOGGING when a database is already on ARCHIVE LOG mode ?
    Create Tablespace
    LOGGING: Generate redo logs for creation of tables, indexes and  partitions, and for subsequent inserts. Recoverable
    Are they not logged and not recoverable if we do not enable LOGGING? What is that ARCHIVELOG mode does?

    What is that ARCHIVELOG Mode Does?
    Whenever your database is in archive log mode , Oracle will backup the redo log files in the form of Archives so that we can recover the database to the consistent state in case of any failure.
    Archive logging is essential for production databases where the loss of a transaction might be fatal.
    Why Logging?
    Logging is safest method to ensure that all the changes made at the tablespace will be captured and available for recovery in the redo logs.
    It is just the level at which we defines:
    Force Logging at DB level
    Logging at Tablespace Level
    Logging at schema Level
    Before the existence of FORCE LOGGING, Oracle provided logging and nologging options. These two options have higher precedence at the schema object level than the tablespace level; therefore, it was possible to override the logging settings at the tablespace level with nologging setting at schema object level.

  • Putting a Oracle RAC in  to archive log mode??

    Our RAC is a 10gR2 Three(3) node RAC with a SAN as the shared storage. cluster is installed on linux. at the moment the RAC is in noarchieve log mode.
    SQL> archive log list;
    Database log mode No Archive Mode
    Automatic archival Disabled
    Archive destination /u01/app/oracle/product/10.2.
    Oldest online log sequence 665
    Current log sequence 666
    we created raw partitions in SAN and use ASM to manage shared storage.
    when running DBCA at "specify locations for the database files to be created" step we selected "use oracle managed files" and gave database area = +DATA/
    then at choose the recovery options for the database" step we ticked specify flash recovery area and gave Flash Recovery AREA = +BACKUP/ and flash recovery area = 10240 MB. we didnt click "enable archiving" option. hence the RAC DB is in NOARCHIEVELOG mode.
    i found some guide to put RAC in archive log mode which i have given below....
    ALTER SYSTEM SET log_archive_start=TRUE SCOPE=spfile;
    ALTER SYSTEM SET log_archive_dest_1='location=/u01/oradata/MYSID/archive/' SCOPE=spfile;
    ALTER SYSTEM SET log_archive_format='arch_%t_%s.arc' SCOPE=spfile;
    Since we need to mount the database in exclusive mode we must also alter the following parameter:
    ALTER SYSTEM SET cluster_database=FALSE SCOPE=spfile;
    From the command line we can stop the entire cluster using:
    srvctl stop database -d MYSID
    With the cluster down we can connect to a single node and issue the following commands:
    ALTER SYSTEM SET cluster_database=TRUE SCOPE=spfile;
    Notice that the CLUSTER_DATABASE parameter has been reset to it's original value. Since the datafiles and spfile are shared between all instances this operation only has to be done from a single node.
    From the command line we can now start the cluster again using:
    srvctl start database -d MYSID
    my main question is about the setting of
    ALTER SYSTEM SET log_archive_dest_1='location= ????? ' SCOPE=spfile;
    since i have set +BACKUP/ as the FRA during installation how should i define the location of log_archive_dest_1???
    many thanks in advance.

    many thanks for the replies
    will the command you posted send the archive logs to the "+BACKUP/" location in my SAN.
    if yes how does oracle know that USE_DB_RECOVERY_FILE_DEST = BACKUP/ in my SAN. or how do i set oracle to use BACKUP/ as the USE_DB_RECOVERY_FILE_DEST??
    im a newbie to RAC so pls bear with me. also at the moment i get the following outputs from my database.... pls note the bold part below, is the archive destination pointing to a location in my local server?
    SQL> archive log list;
    Database log mode No Archive Mode
    Automatic archival Disabled
    Archive destination            /u01/app/oracle/product/10.2.0/db_1/dbs/arch
    Oldest online log sequence 665
    Current log sequence 666
    SQL> show parameter db_recovery;
    db_recovery_file_dest string
    db_recovery_file_dest_size big integer 0
    SQL> show parameter archive
    archive_lag_target integer 0
    log_archive_config string
    log_archive_dest string
    log_archive_dest_1 string
    log_archive_dest_10 string
    log_archive_dest_2 string
    log_archive_dest_3 string
    log_archive_dest_4 string
    log_archive_dest_5 string
    log_archive_dest_6 string
    log_archive_dest_7 string
    log_archive_dest_8 string
    log_archive_dest_9 string
    log_archive_dest_state_1 string enable
    log_archive_dest_state_10 string enable
    log_archive_dest_state_2 string enable
    log_archive_dest_state_3 string enable
    log_archive_dest_state_4 string enable
    log_archive_dest_state_5 string enable
    log_archive_dest_state_6 string enable
    log_archive_dest_state_7 string enable
    log_archive_dest_state_8 string enable
    log_archive_dest_state_9 string enable
    log_archive_duplex_dest string
    log_archive_format string %t_%s_%r.dbf
    log_archive_local_first boolean TRUE
    log_archive_max_processes integer 2
    log_archive_min_succeed_dest integer 1
    log_archive_start boolean FALSE
    log_archive_trace integer 0
    remote_archive_enable string true
    standby_archive_dest string ?/dbs/arch

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