Recovering database with no backup!

Recovering database with no backup!

Post by Yanick Hudo » Tue, 27 Aug 2002 01:18:06



Hi all,

    Sorry if the post is a little bit long, but i think it worth to tell if
ever someone else has the same problem.

    After 3 hard days working on a recovery and some reading with any
advices from you, i succeeded
    to recover my production database but i want more explanation and wich
way i can do a backup right
    away.

    Here's the steps i've made:

    1. Reformat the hard disk;
    2. Reinstall Oracle;
    3. Recreate database (for havin the control files and all data files);
    4. Copy all the datafiles and control files i had on CD to the location
wich Oracle put them;
    5. After the message: ORA-00600: ORACLE initialization in progress or
shutdown when i tried to connect:
        a) I started RMAN and issued the following command: RECOVER
DATABASE;
            and RESTORE DATABASE;
        b) I still got errors on those command, i started Oracle Entreprise
Manager to see the database status;
        c) It gives me Status Mounted, so i tried to open the database and
on each time it gave me the missing
            files;
        d) I copied the files requested to the locations that Oracle
Enterprise Manager was telling me;
    6. When the database got the status open, i succeed to start SQL on the
database and all the datas were there.

    BTW: If ever you're using tablespace, be sure to have a copy of them
when doing this procedure, otherwise
              i think taht you won't be able to recover.

    Now the lessons i've got from this crash:

    1) Be sure to always have a backup of the database (even if i still
don't know how);
    2) If #1 is not available, at least get a copy of all the control files,
data files, tablespace you're using;
    3) If you don't have #1 or #2, you're in real trouble.

    Last thing: When you're doing this procedure, ensure that you'll be able
to recreate all the disk partitions
                     like they were before (logical, extended, and physical
partitions).

    Thanks to all who helped me in this wonderful adventure.

 
 
 

Recovering database with no backup!

Post by Richard Foot » Tue, 27 Aug 2002 12:58:19


Hi Yanick,

Sounds like you had a bit of fun these past few days. That's the ticket ;)

At the risk of repeating myself, there are three key things (or golden
rules) you require to completely recover your database:

1) A complete backup of your database that includes as a minimum your
control files and all your data files. It doesn't particularly matter if
this backup is hot or cold so long as the backup is on a separate device
from your original files (as someone on a recent thread learnt the hard
way).

2) All the redo logs generated since the oldest backed up file (and the only
way to guarantee this is to have your database running in archivelog mode)

3) A DBA who knows what they are doing ;)

With respect to rule 1, if you don't backup your database, then recovery
becomes a tad difficult. The only exception to the backup rule is if you
have created a tablespace (or added a new datafile to an existing
tablespace) between your regular backups. So long as you have all the redo
logs that have been generated since the new datafile was created (which rule
2 suggests you should have), then complete recovery is still possible.
Instead of restoring the corrupt datafile you can simply recreate the file
with the ALTER DATABASE CREATE DATAFILE command and complete recovery as
normal.

With respect to rule 2, the redo logs are possibly more important than the
backup files themselves (as suggested above). If you don't ensure a complete
set of redo logs between backups, then you are suggesting a complete restore
from a previous backup is an acceptable recovery strategy (and the
subsequent loss of changes). If it is great, if it isn't then protect these
little mammas.

With respect to rule 3, you are on your way to meeting this criteria. It
only comes with adequate training and experience. Proactive testing of both
your backup strategies and of your personal skills will help to ensure you
know what to do when you really need to.

If you remember the three golden rules then you're going to be OK and
worrying about how to recover a database with no backup becomes an
irrelevant issue.

Cheers

Richard


Quote:> Hi all,

>     Sorry if the post is a little bit long, but i think it worth to tell
if
> ever someone else has the same problem.

>     After 3 hard days working on a recovery and some reading with any
> advices from you, i succeeded
>     to recover my production database but i want more explanation and wich
> way i can do a backup right
>     away.

>     Here's the steps i've made:

>     1. Reformat the hard disk;
>     2. Reinstall Oracle;
>     3. Recreate database (for havin the control files and all data files);
>     4. Copy all the datafiles and control files i had on CD to the
location
> wich Oracle put them;
>     5. After the message: ORA-00600: ORACLE initialization in progress or
> shutdown when i tried to connect:
>         a) I started RMAN and issued the following command: RECOVER
> DATABASE;
>             and RESTORE DATABASE;
>         b) I still got errors on those command, i started Oracle
Entreprise
> Manager to see the database status;
>         c) It gives me Status Mounted, so i tried to open the database and
> on each time it gave me the missing
>             files;
>         d) I copied the files requested to the locations that Oracle
> Enterprise Manager was telling me;
>     6. When the database got the status open, i succeed to start SQL on
the
> database and all the datas were there.

>     BTW: If ever you're using tablespace, be sure to have a copy of them
> when doing this procedure, otherwise
>               i think taht you won't be able to recover.

>     Now the lessons i've got from this crash:

>     1) Be sure to always have a backup of the database (even if i still
> don't know how);
>     2) If #1 is not available, at least get a copy of all the control
files,
> data files, tablespace you're using;
>     3) If you don't have #1 or #2, you're in real trouble.

>     Last thing: When you're doing this procedure, ensure that you'll be
able
> to recreate all the disk partitions
>                      like they were before (logical, extended, and
physical
> partitions).

>     Thanks to all who helped me in this wonderful adventure.


 
 
 

Recovering database with no backup!

Post by Ed Procha » Sat, 31 Aug 2002 03:41:09



Quote:> Hi all,

>     Sorry if the post is a little bit long, but i think it worth to
tell if
> ever someone else has the same problem.

>     After 3 hard days working on a recovery and some reading with
any
> advices from you, i succeeded

[]

Quote:>     Now the lessons i've got from this crash:

>     1) Be sure to always have a backup of the database (even if i
still
> don't know how);
>     2) If #1 is not available, at least get a copy of all the
control files,
> data files, tablespace you're using;
>     3) If you don't have #1 or #2, you're in real trouble.

>     Last thing: When you're doing this procedure, ensure that you'll
be able
> to recreate all the disk partitions
>                      like they were before (logical, extended, and
physical
> partitions).

>     Thanks to all who helped me in this wonderful adventure.

Primary rule of backup and recovery: It doesn't work until you test
it.

IOW do  trial run of you recovery process before you have  crash.

 
 
 

1. copy database, change SID, create cntrlfile and recover using backup controlfile

Hello

I want to copy a complete source-DB database to the test-system.
1. I take the files from a OFFline backup.
2. I do a create controlfile with a modified controlfile from the
source-DB in nomount status. Modifications: DBNAME, Path to datafiles,
...
3. When I try to recover database using backup controlfile,
can I carry on recovery after reaching the log-sequence-number/SCN of
the (consistant) datafiles or not???
I want to recover until last offline redo!

thx for your help
Johannes

--
***  "First think and than do and do not forget    ***
***   each of them", the old, wise man said.       ***

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