Oracle FAQ Your Portal to the Oracle Knowledge Grid
HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US
 

Home -> Community -> Mailing Lists -> Oracle-L -> RE: Undocumented Instance/Media Recover Feature?

RE: Undocumented Instance/Media Recover Feature?

From: Powell, Mark D <mark.powell_at_eds.com>
Date: Wed, 26 May 2004 13:02:00 -0400
Message-ID: <564DE4477544D411AD2C00508BDF0B6A1CE0AB5B@usahm018.exmi01.exch.eds.com>


I have seen problems related to the control file before but I cannot remember the exact details since it was a VMS specific bug for version 7.0.15 (if my memory is correct) that required us to recreate the control file by editing the file information in the script created by a backup control file to trace command.

I have also seen system tables out of sync with each other. Specifically, uet$ and fet$ where Oracle manages free and used extents. There was a little problem related to truncate where if you cancelled the truncate the entire instance might crash and if did these two base tables may not contain information about an extent (or maybe it was that an extent would show as both used and free). It was a generic UNIX version bug with what was probably version 7.1. That was a fun tar! Funny things like this can and do sometimes happen.

In this case dropping the "missing" tablespace and recreateing the index in the tablespace you want it in will fix everything so that may be the best course followed by wait and see.

Good luck.

-----Original Message-----
From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org]On Behalf Of Orr, Steve Sent: Wednesday, May 26, 2004 12:28 PM
To: oracle-l_at_freelists.org
Subject: RE: Undocumented Instance/Media Recover Feature?

> Was an old or backup control file used to start the db=20
Nope. And I never witnessed any datadictionary views that weren't in sync with the control files.

-----Original Message-----
From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Powell, Mark D Sent: Wednesday, May 26, 2004 10:17 AM
To: 'oracle-l_at_freelists.org'
Subject: RE: Undocumented Instance/Media Recover Feature?

Pardon me if I am butting in but I think because the information in the control file does not match up to sys.file$ which ties file numbers to tablespaces. There apparently is a file# in file$ that is not in the control file.

Was an old or backup control file used to start the db by the other DBA/Developer?

-----Original Message-----
From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org]On Behalf Of Orr, Steve Sent: Wednesday, May 26, 2004 11:58 AM
To: oracle-l_at_freelists.org
Subject: RE: Undocumented Instance/Media Recover Feature?

The curiousity is that the file didn't exist in the O/S, Oracle created it without telling me, and it created and placed a database object into that file, again, without telling me. I just stumbled across this but I'd like to KNOW when this happens.

V$DATAFILE and V$TABLESPACE get information from the control file so how could they be out of sync?=3D20

-----Original Message-----
From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Tim Johnston Sent: Wednesday, May 26, 2004 9:46 AM
To: oracle-l_at_freelists.org
Subject: Re: Undocumented Instance/Media Recover Feature?

Hi Steve...

  I believe you are seeing a mismatch between the controlfile and = the=3D20
data dictionary... Basically, you started up your database and the data

dictionary says you have tablespace "blah" associated with file id "x"=3D20 but the controlfile doesn't have a file for that tablespace... So, it=3D20 places a dummy placeholder file in it's place... You can simulate this=3D20 but doing the following:

$ sqlplus "/ as sysdba"

SQL*Plus: Release 9.2.0.3.0 - Production on Wed May 26 11:37:32 2004

Copyright (c) 1982, 2002, Oracle Corporation. All rights reserved.

Connected to an idle instance.

SQL> Create Tablespace Tim Datafile '/export/home/oradata/PV429/tim.dbf' size 10M;

Tablespace created.

SQL> alter database backup controlfile to trace;

Database altered.

SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> Then edit the create control file command and removed the line for the=3D20 newly created datafile...

$ sqlplus "/ as sysdba"

SQL*Plus: Release 9.2.0.3.0 - Production on Wed May 26 11:40:21 2004

Copyright (c) 1982, 2002, Oracle Corporation. All rights reserved.

Connected to an idle instance.

SQL> startup nomount
ORACLE instance started.

Total System Global Area 252793548 bytes

Fixed Size                   455372 bytes
Variable Size             167772160 bytes
Database Buffers           83886080 bytes
Redo Buffers                 679936 bytes
SQL> @cre_control

Control file created.

SQL> alter database open;

Database altered.

SQL> set pagesize 1000                             =3D20
SQL> select * from dba_data_files where tablespace_name =3D3D 'TIM';

FILE_NAME



   FILE_ID TABLESPACE_NAME                     BYTES     BLOCKS STATUS
---------- ------------------------------ ---------- ----------


RELATIVE_FNO AUT MAXBYTES MAXBLOCKS INCREMENT_BY USER_BYTES USER_BLOCKS
------------ --- ---------- ---------- ------------ ----------

/opt/oracle/product/9.2.0/dbs/MISSING00035

        35 TIM
AVAILABLE
          35

SQL> Tim

Orr, Steve wrote:

>We have this QA database which I can mostly ignore but Mr. QA dude found
>a bug caused by the compatible init.ora parameter not being properly=20 >set. Since they kind of admin their own database and know the timing of

>their database availability needs for QA testing, I gave QA dude=20
>instructions on recycling the database... "SQL> shutdown abort" and=20
>"SQL> startup"=3D3D20
>
>But the database didn't come back up due to a shared memory error so I=20
>figured I'd have to fix things with ipcs/ipcrm. But before getting into

>that I just tried "SQL> startup" myself and behold, everything started=20
>up just fine with no warning messages or anything. Hmmm... That's=20
>curious... I guess the oracle just likes me better. I was in=20
>$ORACLE_HOME/dbs verifying the existence of the "lk$ORACLE_SID" file=20 >when I saw something curious... A 100MB file named "MISSING00042" which

>had the same database startup timestamp as the lk$ORACLE_SID file and=20 >wondered what it was and where it came from. So I queried dba_data_files
>and the data file with file_id 42 has the path of=20 >$ORACLE_HOME/dbs/MISSING00042. Whoa!!! That directory path and 100MB are
>the default values when using Oracle-managed files and 42 is the answer

>to all things! But we don't use Oracle-managed files. Curious but how=20 >could the oracle create this datafile automagically for me and not even

>tell me? Where's it going to get the data? Then I look at dba_segments=20
>and see that there's only one object in that tablespace/datafile, an=20
>index which could be rebuilt from the data in another tablespace the=20
>table is in. Does this mean that the oracle couldn't find the datafile=20
>but created it for me automagically just because it could and because=20
>the only object was an index?=3D3D20
>
>Has anybody seen this behavior before? Is there any documentation on
it?
>Running Oracle 9.2.0.4 on Linux.
>
>
>Steve Orr
>Curious in Bozeman, Montana
>----------------------------------------------------------------
>Please see the official ORACLE-L FAQ: http://www.orafaq.com
>----------------------------------------------------------------
>To unsubscribe send email to:  oracle-l-request_at_freelists.org put=20
>'unsubscribe' in the subject line.
>--
>Archives are at http://www.freelists.org/archives/oracle-l/
>FAQ is at http://www.freelists.org/help/fom-serve/cache/1.html
>-----------------------------------------------------------------

> =3D20

>

--=3D20
Regards,
Tim Johnston
Tel: 978-322-4226
Fax: 978-322-4100



Please see the official ORACLE-L FAQ: http://www.orafaq.com

To unsubscribe send email to: oracle-l-request_at_freelists.org put 'unsubscribe' in the subject line.
--
Archives are at http://www.freelists.org/archives/oracle-l/
FAQ is at http://www.freelists.org/help/fom-serve/cache/1.html
-----------------------------------------------------------------

----------------------------------------------------------------
Please see the official ORACLE-L FAQ: http://www.orafaq.com
----------------------------------------------------------------
To unsubscribe send email to:  oracle-l-request_at_freelists.org put
'unsubscribe' in the subject line.
--
Archives are at http://www.freelists.org/archives/oracle-l/
FAQ is at http://www.freelists.org/help/fom-serve/cache/1.html
-----------------------------------------------------------------
----------------------------------------------------------------
Please see the official ORACLE-L FAQ: http://www.orafaq.com
----------------------------------------------------------------
To unsubscribe send email to:  oracle-l-request_at_freelists.org put
'unsubscribe' in the subject line.
--
Archives are at http://www.freelists.org/archives/oracle-l/
FAQ is at http://www.freelists.org/help/fom-serve/cache/1.html
-----------------------------------------------------------------

----------------------------------------------------------------
Please see the official ORACLE-L FAQ: http://www.orafaq.com
----------------------------------------------------------------
To unsubscribe send email to:  oracle-l-request_at_freelists.org
put 'unsubscribe' in the subject line.
--
Archives are at http://www.freelists.org/archives/oracle-l/
FAQ is at http://www.freelists.org/help/fom-serve/cache/1.html
-----------------------------------------------------------------
----------------------------------------------------------------
Please see the official ORACLE-L FAQ: http://www.orafaq.com
----------------------------------------------------------------
To unsubscribe send email to:  oracle-l-request_at_freelists.org
put 'unsubscribe' in the subject line.
--
Archives are at http://www.freelists.org/archives/oracle-l/
FAQ is at http://www.freelists.org/help/fom-serve/cache/1.html
-----------------------------------------------------------------
Received on Wed May 26 2004 - 12:00:23 CDT

Original text of this message

HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US