Why we cannot take hot backup if database is in noarchive log mode

I am aware that if database is in noarchive log mode, we cannot take hot backups and only cold backup is possible.
I would like to know the technical reason behind this restriction?
Thank You

Hot backups are fuzzy backups, inconsistent, in other words, since something is always happening in the database.  When you recover, you restore data files and then apply redo to make the transactions consistent.  You can do a complete recovery or recover to a point in time.  So where does the redo come from?  That's what we call archiving redo logs.  When the online redo gets full, it gets archived.
In the case of an instance crash, the redo is there in the online redo logs, so Oracle can recover automatically.  Anything beyond that, having to do with storage media, is a media recovery, and requires those archived logs.  So unless you have some other way to get your data back, always run in archivelog mode.
It is really important to understand the concepts.  Please read the docs.
It may be worth your while to get a third party backup and recovery book too.

Similar Messages

  • Hot Backup Of Database

    How much time would oracle take if I take Hot Backup (using Imp/Exp statement) of a 60 GB database? Are there some other ways also of taking Hot BackUp ? How much would it effect oracle's performance while backup is taking place as the database is 24 x 7 and is taking uploads every few seconds?

    Do not use IMP/EXP as a backup strategy. These utilities are intended for moving data about. Backup means taking a copy of the OS files - data files, redo logs, etc. To find out more please read the docs.
    Cheers, APC

  • Why i cannot create the sql azure database from my own country 'Nepal' ?. why it is not include in the list of country when we sign up for azure database. :( !!!

    why i cannot create the sql azure database from my own country 'Nepal' ?. why it is not include in the list of country when we sign up for azure database. :(  !!!
    canot we try this new feature ,dosnot we need to try this too..why such discermination for our country nepal. :(

    Hi Anil,
    I am Mahesh from Microsoft Innovation Center. From August 2014 we have made Azure Available to Nepal. You can now directly sign in to azure with your Nepal Based Mobile Number as Verification.
    Thanks for showing your Interest in our Product.
    Mahesh Dahal

  • Minimum  privilege is required to take hot backup

    which privilege is required to take hot backup i want create user to take hotbackup with minimum privilege .now i take hotbackup with SYS user but this is danger because another department should be take hotbackup.
    best regards
    Edited by: Allahmorad on Sep 22, 2011 12:08 AM

    Please see below for your issue:
    Privileges required for RMAN backup

  • Backup of the database failed Showing: Unknown log mode : SP2-0640:.

    In Oracle Express Edition 10g:
    When I try to create a backup I get the following:
    ==================== ERROR =============================
    Backup of the database failed.
    Unknown log mode : SP2-0640:.
    Log file is at SP2-0640:.
    ==================== ERROR =============================
    Press any key to continue . . .
    What may be the reason and whats the solution

    Hi all,
    I had the exact same problem
    the backup menu item runs :
    when you look at this batchfile you will see the following :
    The script assumes that user can connect using "/ as sysdba"when you have OS authentication disabled the batchfile will give the formentioned error
    turn OS authentication back on by changing C:\oraclexe\app\oracle\product\10.2.0\server\NETWORK\ADMIN\sqlnet.ora
    (you could turn it back off after your backup succeeded)

  • RMAN backup in noarchived log mode

    can we take RMAN backup in noarchived log mode?
    If yes, how? just run backup database command or ?

    You can use RMAN to backup a database in noarchivelog mode but you need to shutdown and mount the database. e.g.:
    rman target /
    RMAN> shutdown immediate
    RMAN> startup mount
    RMAN> backup database

  • When i start my hot backup my database getting very slow

    I am using following commands for enabling hot backup
    Database altered.
    1 ACTIVE
    2 ACTIVE
    3 ACTIVE
    4 ACTIVE
    and using cp -rp command to copy the file (backup copying speed good) but database performance very slow
    How to improve performance ...
    Vignesh C

    Uwe Hesse wrote:
    It is very likely that you experience slow performance with ALTER DATABASE BEGIN BACKUP , because until you do ALTER DATABASE END BACKUP , every modified block is additionally written into the online logfiles . Doesn't that happen only the first time the block is modified?
    The command was introduced for split mirror backups, when this period is very short. Else ALTER TABLESPACE ... BEGIN/END BACKUP for every tablespace one at a time reduces the amount of additional redo during non-RMAN Hot Backup. There appear to be only 4 files. We don't know how big or sparse they are.
    RMAN doesn't need that at all - much less redo - and also archive - generation then.
    Furthermore, you can use BACKUP AS COMPRESSED BACKUPSET DATABASE to decrease the size of the backup even more - if space is an issue.
    In short: Use RMAN :-)
    Agree with that! Unless the copy is actually going to an NFS mount or something, where I would be concerned whether it is the type of NFS that Oracle likes. I'd also advise a current patch set, as the OP didn't tell us the exact version, and I have this nagging unfocused memory of some compression problems of the "oh, I can't recover" variety.
    I'd like to see some evidence on I/O and cpu usage before giving advice. When I used to copy files like this, it would choke out everyone else. RMAN was a savior, but had to wait for local SAN upgrade.

  • Clone database with no archive log mode and downtime with new file structure

    We need to clone database with following business requirements :
    No downtime at all can be afford
    databases are in no archive log mode
    data-file locations need to be change to new mount points while cloning for space management factor
    Please suggest the best possible methods for same ?

    Can you post your version of oracle in 4 digits and OS for better understandig
    I dont think you can move the No Archive database to a new location without shutting down.
    You just want to move them to the new mount points is it?
    1. How big are your datafiles are?
    2.How do you backup this DB?
    When you move the datafilles then it becomes inconsistent and you need redo logs and probably archive logs to be there to make the file consistent or else it would be prompting for recovery. The chances are your redolog will be overwritten and hence you wont be able to recover.
    You need downtime.

  • Backup while database are running in replication mode

    We have to devise the stratgey for backup and restore of database which are involed into repliation e.g. master database and snapshot database

    I am sorry, but all of the iPad content is gone now. With no backup, there is no way to retrieve anything. You cannot backup now either. Use recovery mode, restore your iPad and download your content again and start all over. You have no choice.

  • Hot Backup for oracle database?

    Dear all,
    I want to change Cold Backup to Hot Backup. Does anyone how to do Hot Backup and has some simple document I can follow? If the database is running in ARCHIVELOG mode, is the size grow very fast or other effect will overcome?
    Please advice,

    I want to change Cold Backup to Hot Backup. Does
    anyone how to do Hot Backup and has some simple
    document I can follow?online/hot backup don’t need to shutdown the database we can put the database in backup mode and then start taking backup even though users database activity read/write data going on. This strategy useful if ours database goes for 24x7.
    For online/hot backup the database should be in archive mode.
    I hope you know how to turn on archive.Before turning on check the archive on or not.
    SQL> archive log list
    Database log mode              Archive Mode
    Automatic archival             Enabled
    Archive destination            USE_DB_RECOVERY_FILE_DEST
    Oldest online log sequence     1
    Next log sequence to archive   2
    Current log sequence           2
    SQL> you may also check it by connecting to database as sys
    SQL> select log_mode from v$database;
    SQL> if yours database is not in archive mode then first enable archive,please before turning on the archive take cold backup.
    SQL>shutdown immediate
    SQL>startup mount
    SQL>alter database archivelog
    SQL>alter database open;
    SQL> archive log list
    Now you are able to take hot/online backup ,its upto you you use user managed backup and recovery or use RMAN oracle own shipped free tool for backup and recovery ,however my recommendation would goes for RMAN.
    ARCHIVELOG mode, is the size grow very fast or other
    effect will overcome?However, the growing size pace either fast or slow everyday can be impractical it alls depends on activity of yours database operation.You will have to observe it yourself by turning on archive log its vary database to database activity.

  • Backup Oracle Database whilst online

    Guys looking for some help, I have an Oracle database that must run 24hours a day but I need to be able to back this database up daily, from what I understand I have to make the database run in archive log mode to be able to perform a hot backup.
    I have found out that currently my database is in noarchive log mode
    Can someone help me with the commands to put the database is achivelog mode
    Then can you help me with the command to backup the database using RMAN I have read some documentation do I need to just issue the backup database command or do I need to backup the archive logs files as well ?

    Do you want to teach me lesson ? I'm working with Oracle database since 1988, and I'm using RMAN since version 8.0 (15 years ago, or so).
    And please read the link I posted above.
    1) ... At lease two redo logs destination is recommended so that one redolog destination is keep working while other is filled up or vice versa.
    And you think I don't know that ? And that's not multiplexing.
    2) Catalog database is optional but it is recommended.
    It's absolutely not needed, and I consider it just and overhead (another database to manage and to synchronize).
    3) You need to setup archivelog retention policy so that it cleans up from LOG destination after certain period of time.
    You use DELETE INPUT option in your script, but it looks like you don't know what it means.
    Please follow oracle documentation for best practice .
    Again, are you teaching me lesson ? Oracle documentation is my bible.
    Backup is very important for a DBA so you need to set up precisely so that you can recover the database during disaster
    Backup is very important for a DBA ? What a news !! About disaster recovery, at your #1 you said "redo logs are very important to restore database" : or we mean something different for "disaster recovery", or you are totally wrong.

  • How to take a Hot backup of Oracle database

    1: put the db in archive log mode
    2: set the db_sid to correct one
    3: login to sqlplus
    4: verify the name of the db that you are connected to
    select name from v$database;
    5: check if the db is in archive log made
    select log_mode from v$database;
    if not in archive log mode
    another command to check
    archive log list;
    6: find where on disk oracle writes archive log when it is in archive log mode
    sql> show parameter log_archive_dest_1;
    if the value is found to be 0, that means no values will be recorded, so we need to change it
    sql> alter system set log_archive_dest_1='LOCATION=c:\database\oradata\finance\archived_logs\'
    7: shutdown immediate; < this is done just to prepare the db for hot backups >
    8: startup the db in mount mode
    startup mount;
    ( 3 startup types : nomount - just starts the instance, mount - locates the control files and open up according to the values, open - finds the datafiles from the control files and opens up the db )
    9: put the db in archive log mode
    alter database archivelog;
    10: open the database
    alter database open;
    11: check the status of the db
    select log_mode from v$database;
    SQL> archive log list;
    12: create a directory for archived log
    check if its empty, if empty we need to switch
    sql> alter system archive log current;
    run it 5 times < need to put / and enter > , then check the archive log dir , we will find files
    13: make a table in the database and insert data in it
    create table employees (fname varchar(2));
    check the table
    desc employees;
    insert values
    insert into employees values ('Mica');
    14: tablespace must be in hot backup mode
    check the status
    select * from v$backup;
    if found not active, then we need to change
    we cannot put the db in hot backup mode, unless it is archive log mode
    change to hot backup mode
    alter database begin backup;
    check the status
    select * from v$backup;
    15: now we can only COPY DBF FILES
    copy *dbf <distination location>
    16: need to take the db out to hot backup mode
    alter database end backup;
    17: need to make another archive log switch
    alter system archive log current;
    18: need to copy control files now, need to do a binary bckup
    alter database backup controlfile to '<location>\controlbackup';
    19: insert more values to the table
    insert into employess values ('NASH')
    make another archive log switch : alter system archive log current;
    do the same process for more values
    20 : backup all the archive logs to a new location
    21: shutdown the db and simulate a hw error, delete all the files from the database folder
    22: try to start the sqlplus and db ::: error
    23: copy all the backups to the db dir
    need to copy the control files, rename the binary backup of the control file and make the copies as needed
    24: try to mount the db, error < must use reset logs or noreset logs >
    25: need to do a recovering of the database
    restore the archive logs
    startup mount;
    recover database until cancel using backup controlfile;
    it will ask for a log file :
    yes for recovery
    cancel for cancelling recovery
    26: check status: open the database in readonly
    alter database open read only;
    check the tables to see the data
    shutdown immediate
    shartup mount;
    recover again : recover database until cancel using backup controlfile;
    if oracle is asking for a log that do nto exist , all we have to do is type cancel
    27: open the database
    alter database open;
    need to do reset logs
    alter database open resetlogs;
    28: check the db that you are connected, check the tables
    thanks and regards
    site admin

    A very long list ... let me make it shorter.
    SQL> archive log list;If I see this:
    Database log mode              No Archive ModeI put the database into archivelog mode and leave it there forever.
    If it is in archivelog mode:
    RMAN> TARGET SYS/<password>@<service_name> NOCATALOG
    RMAN> BACKUP DATABASE PLUS ARCHIVELOG;Though there are a lot of things one could do better such as incrementals with block change tracking, creating an RMAN catalog, etc.

  • Why archivelog mode is mandatory for hot backups.

    Why the database should be put in archivelog mode when we take hot backups. What happens actually. Why can't we put in noarchivelog mode and take hot backups?

    Suppose you are not using RMAN then you must put your tablespaces in backup mode. Otherwise the backup you can take will be unrecoverable.
    In order to recover from a Hot Backup you have to do followings
    - Restore your Hot Backup
    - Recover the database - here, the archive log files are important
    How does Oracle know what has to be recovered from archivelogs?It looks at the SCN.
    If you never put your tablespaces in backup mode then SCN would not be frozen and Oracle wouldn't know what has to be recovered.
    Talip Hakan Ozturk

  • Cannot able to take DB Backup to Tape Drive

    I cannot take DB backup from SQL server and also from SAP too. Its getting failure.
    I changed the Tape drive and Tape also.
    SAP DB13 error msg is below:
    Executed as user: NT AUTHORITY\SYSTEM. ...ontact your system administrator. [SQLSTATE 01000] (Message 2528)  Processed 10575360 pages for database 'APP', file 'APPDATA1' on file 1. [SQLSTATE 01000] (Message 4035)  Processed 6256640 pages for database  'APP', file 'APPDATA2' on file 1. [SQLSTATE 01000] (Message 4035)  Processed 6667936 pages for database 'APP', file 'APPDATA3' on file 1. [SQLSTATE 01000] (Message 4035)  Processed 2857 pages for database 'APP', file 'APPLOG1' on file 1. [SQLSTATE 01000] (Message 4035)  BACKUP DATABASE successfully processed 23502793 pages in 2029.133 seconds (94.885 MB/sec). [SQLSTATE 01000] (Message 3014)  Processed 1568 pages for database 'master', file 'master' on file 2. [SQLSTATE 01000] (Message 4035)  Processed 1 pages for database 'master', file 'mastlog' on file 2. [SQLSTATE 01000] (Message 4035)  BACKUP DATABASE successfully processed 1569 pages in 8.052 seconds (1.595MB/sec). [SQLSTATE 01000] (Message 3014)  Processed 3016 pages for database 'ms...  The step failed.

    Hi Thillai,
    Hope the below link helps you.
    How to: Set the Expiration Date on a Backup (SQL Server Management Studio)
    How to: Back Up a Database (SQL Server Management Studio)

  • Rman hot backup

    i am using rman hot backup script to take backup database everyday but the problem is it is working but not deleting old backup older than 2 days .
    also i have question .. my database is in archive log mode and everyday about 6-7 .arch files generating in my archive directory.
    it is not deleting the old files but generating new files everyday so adding up to the space.
    SQL> show parameter archive
    archive_lag_target integer 0
    log_archive_config string
    log_archive_dest string /u03/archive_logs/DEVL
    log_archive_dest_1 string
    also should i set dest_1 as archive location or just log_archive_dest
    whats is the difference.?
    my rman script is
    RMAN Hot backup.unix script
    The RMAN hot backup script rman_backup.sh:
    # !/bin/bash
    # Declare your environment variables
    export ORACLE_SID=DEVL
    export ORACLE_BASE=/u01/app/oracle
    export ORACLE_HOME=/u01/app/oracle/product/11.2.0/db_1
    export PATH=$PATH:${ORACLE_HOME}/bin
    # Start the rman commands
    rman target=/ << EOF
    run {
    allocate channel d1 type disk;
    allocate channel d2 type disk;
    allocate channel d3 type disk;
    allocate channel d4 type disk;
    BACKUP AS COMPRESSED BACKUPSET DATABASE FORMAT '/u03/backup/databasefiles_%d_%u_%s_%T';

    Ahmer Mansoor wrote:
    RMAN never deletes the Backups unless there is a space pressure in the Recovery Area. Instead it marks the Backups as OBSOLETE based on Retention Policy (in your case it is 2 Days),
    To confirm it SET DB_RECOVERY_FILE_DEST_SIZE to some smaller value, the RMAN will remove all the Obsolete Backups automatically to reclaim space.Be very careful with this. If you generate a LOT of archivelog files and you exceed this size, on the next archivelog switch your database will hang with "cannot continue until archiver freed". RMAN will not automatically remove anything. RMAN only removes stuff when you program it in your script.
    http://docs.oracle.com/cd/E14072_01/backup.112/e10642/rcmconfb.htm#insertedID4 Retention Policy (recovery window or redundancy)
    things like:
    set retention window and number of copies
    crosscheck backup
    delete obsolete <-- delete old, redundant, no longer necessary backups/archivelogs
    delete expired <-- NOTE: If you manually delete files and do not execute delete expired (missing file), the DB_RECOVERY_FILE_DEST_SIZE remains the same. So, you can clean out the space and oracle will still say the location is "full".
    Understand that if you also set this parameter too small and your backup recovery window/redundancy are incorrectly set, you can also exhaust the "logical" space of this location again, putting your database at risk. Your parameter could be set to 100G on a 400G file system and even though you have 300G available, Oracle will see the limit of this parameter.
    My suggestion, get in a DEV/TEST environment and test to see how to best configure your environment for RMAN database backups/control file, archivelog backups also taking into consideration OS tape backup solutions. I always configure DISK for RMAN backups, then have some other tape backup utility sweep those locations to tape ensuring that I have sufficient backups to reconstitute my database - I also include a copy of the init.ora file, password file as well as the spfile backup in this location.
    In case of Archivelogs, It is better to create and execute a Purge Job to remove Archivelogs after backup them on tape.I almost agree. I try to keep all archivelogs necessary for recovery from last full backup online. I try to keep a full backup online as well. much faster at restoring stuff instead of trying to locate it on tape.

Maybe you are looking for