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Thread: B&R strategy

  1. #1
    Join Date
    Apr 2001
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    112

    B&R strategy

    Hi
    I wanted to find out about the several options available for a backup strategy for a huge database running in Archive mode.

    How is the B& R strategy formulated for real world databases such as financial companies where this is considered very critical aspect for a DBA's job.


    1)If you have data in in the range of 50GB- 200GB with fair amt of transactions happening(not too excessive) , how often should the archive logs should be offloaded to some other storage?
    2)What type of issues and problems are encountered by DBAs while establishing this strategy?
    3)What is a level 1 , level 2 backup?

    Any other information is also appreciated.

    Thanks

  2. #2
    Join Date
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  3. #3
    Join Date
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    1. depends. How much data can you lose?
    2. With backing up only 200G, you shouldn't have very many problems. Make sure you can complete your backups in the prescribed window on n-1 tape drives. Use Hot backups with RMAN.
    3. With only 200G, I wouldn't worry about anything more than a full backup (level 0).
    Jeff Hunter

  4. #4
    Join Date
    Jan 2001
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    Originally posted by marist89

    3. With only 200G, I wouldn't worry about anything more than a full backup (level 0).
    Hi Marist

    well the maximium size of databases that i have ever administered is 80G..now i agree with you of level 0 backup with RMAN for me..Can you tell me from your exeperinces what is the database size till which you will go for level 0 backup after which you would start of thinkin of increamental backup strategy..

    regards
    Hrishy

  5. #5
    Join Date
    Nov 2002
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    New Delhi, INDIA
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    Hi,

    What i prefer is :
    1. Level 0 backup on sundays including archive logs.
    2. Level 2 backup on Tuesday nights including archive logs.
    3. Level 2 backup on Thrusday nights including archive logs.
    4. Remove Archive logs every fortnight from the disk ofcourse after level 0 backup.

    i keep the backup sets for atleast two months before reusing the tapes

    HTH
    Amar
    "There is a difference between knowing the path and walking the path."

    Amar's Blog  Get Firefox!

  6. #6
    Join Date
    Jan 2001
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    Hi Amar

    Tahnks for responding..now hwta i understand for your recover is if there is a media failure resulting in loss of datafiles on

    wednesday
    ---------
    Then you restore the last sundays backup level 0 backup and tuesday nights level 2 backup and apply all the archive logs

    tuesday
    --------
    Then you apply the level 0 backup of last sunday and start applying the archive logs generated on monday to tuesady upto the point of failure..

    Now i am interested in the time to recover in your case on a given tuesday and on a given wednesday ..Also please share the size of your database and hardware details like cpu ,ram etc

    regards
    Hrishy

  7. #7
    Join Date
    Nov 2002
    Location
    New Delhi, INDIA
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    Hi,

    Since my DB's are not big... hardly 8 DBs of 80GB size on average...
    Takes about 5 to 10 mins for recovery (happened once). The RMAN backups were on the disk it self.

    Let me elaborate a little more
    OS IBM AIX 4.3.3 on 4 different RS/6000 nodes, 4 CPUs each node, 4 GB RAM each node. 300 GB hard diskspace on each node. Oracle 9i EE 9.2.0.2.0.

    Our strategy:
    1. RMAN for backup manager
    2. Keep RMAN backup-dumps on the disk.
    3. Copy the dumps to tape later.
    4. We keep the dumps on the disk from Sunday to Sunday. Makes backup as well as recovery faster.

    HTH
    Amar
    "There is a difference between knowing the path and walking the path."

    Amar's Blog  Get Firefox!

  8. #8
    Join Date
    Jan 2001
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    Hi Amar

    Tahnk you very very for the info..this is really great as my databases are also on an average 80Gb only..now i am wundering how did you recover..what i mean was the recovery scenario more like the one i explained on tuesday or was it more like on wednesday..i am just wunderin in which scenario it took 10 minutes with the hardware described

    regards
    Hrishy

  9. #9
    Join Date
    Nov 2002
    Location
    New Delhi, INDIA
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    Hi,
    We lost one datafile when one of my colleagues was copying dbf files of one of the databases to another filesystem.

    What happened was there were two datafiles named t_rdm_01.dbf and t_rdm_02.dbf.

    The command he gave was

    $ cp t_rdm*
    and forgot to mention the directory
    so t_rdm_01.dbf overwrote t_rdm_02.dbf

    That was the only case when we needed recovery and it happened on sunday night and no user was logged in so used only the level 0 backup and archive logs. Good that we take backup before doing any R&D . The file was hardly 300MB and we had the level 0 backup on disk itself.

    We are carefull now we have set the parameter
    alias -x cp='cp -i'
    in the /etc/profile so that such incidents don't happen again.

    HTH

    Regards
    Amar
    "There is a difference between knowing the path and walking the path."

    Amar's Blog  Get Firefox!

  10. #10
    Join Date
    Jan 2001
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    Hi Amar

    Thank you very much for the response and patiently answerin all the questions..well your story reminds me of somethin..in one of those interviews i was asked how many times have i done recovery..when i said that i have not done any recovery in any of my systems except for testing purposes the interviewer was shocked :-)..well amar its gald to know that even you have done recovery only once :-) in real environment :-)

    regards
    Hrishy

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