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Thread: Urgent: Database recovery

  1. #11
    Join Date
    Nov 2000
    Posts
    212
    recovery from 'ora-01194: file 1 needs more recovery to be consistent' may depend if your database is or is not in archivelog mode. When I talked about online redo log required to get out of this error, I was talking about scenariou when database was in NOARCHIVELOG. In such case the only logs one can use for recovery are online logs...

  2. #12
    Join Date
    Jan 2000
    Posts
    387

    Smile

    Hi,

    I am sorry that maybe I did not make myself clear enough or i have make a mistake when I explained the situations and asking questions. :P I am asking for 2 different recovery methods: (1) recover using physcial backup (using tape ,without archiving) for a 24x7 hrs database (2) recover using full export

    (1) For physical backup, there is a chance that controlfile sequence no might jumped during backup and when recover, there will be an error stating that the 'ora-01207:file is more recent than controlfile - old controlfile'. How am I going to solve this error?

    (2) As for full export backup, am i able to recover the database by just importing? do i have to create any controlfiles or tablespaces?

    Pls advice, thank u so much!

  3. #13
    Join Date
    Nov 2000
    Posts
    212
    old control file error can be resolved via backup control file clause.
    It instructs Oracle to do a recovery on restored datafiles that are checkpointed after control file backup was done.
    Normally control file is backuped after datafiles, thus it is more recent.

    full database import/export is different approach:

    recovery deals with database at block level, w/o knowing what is in database.

    exp/imp utility deals with database at sql level: it just runs sql(DDL and DML to load table data) stored in dump file on some already precreated database.

    The difference is in speed ( full database import via imp is slow process), accuracy(at block level you can be sure that you will get database clone, with full db imp it is not so trivial at all), granurality (you can not recover separate tables with recovery), migration(recovery is limited to oracle version, platform and init.ora parameters, mostly db block size, exp/imp can be used to migrate database).


  4. #14
    Join Date
    Jan 2000
    Posts
    387

    Question

    HI,

    If during my physical backup to tape, I start to backup all the datafiles first and backup the controlfile as the last one to have the last sequence number. In this case, will I be able to avoid the old controlfile error? Will this be able to work? Thanks!

  5. #15
    Join Date
    Jun 2000
    Location
    Madrid, Spain
    Posts
    7,447
    letīs clear something up

    Are you in archive log mode? Because you said
    "I am asking for 2 different recovery methods: (1) recover using physcial backup (using tape ,without archiving) " without archiving what do you mean?

    you can backup control file in two ways, a binary copy and a SQL like script to recreate the control file, which one do you have?

  6. #16
    Join Date
    Nov 2000
    Posts
    212
    do you use rman for backups? if so, then it includes controlfile in backup set properly if database backup is done. Otherwise most backup scripts for RMAN use kind of that sequence:

    tablespaces(i.e. datafiles)
    control file
    archive logs (issue archive log before to archive online redo logs)

    If you use alter tablespace begin/end backup and os utility, then I suppose you need to backup controlfile after tablespace backup (at least after alter tablespace begin backup).

    Look into metalink for more regarding those non-rman issues.

  7. #17
    Join Date
    Nov 2000
    Posts
    212
    anyway, for 24x7 db backups are pretty useless. How long it will take to restore from tape? Then to recover(apply all logs)?

    Standby database or may be replication is a good method for 24x7. We rely on standby database and it saved us couple of times.

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