Recover system.dbf with no backup

[wanyue]

hi, hope someone can help. we've no backup.

database cannot be started. we need to recover system.dbf, or otherwise the entire database must be rebuilt.

*** 2002.07.10.08.45.12.000
SMON: following errors trapped and ignored:
ORA-00604: error occurred at recursive SQL level 1
ORA-01115: IO error reading block from file 1 (block # 584)
ORA-01110: data file 1: '/u2/GEMS/systemxxxx.dbf'
ORA-27072: skgfdisp: I/O error
IBM AIX RISC System/6000 Error: 11: Resource temporarily unavailable

[annli]

Any change made before you've got such error? I wonder if it's due to file corruption or just improper file permission setting at OS level

[wanyue]

no changes is made. we guess file is corrupted.

we've all the database files available, is there a way to 'cheat' the system in recovering system.dbf?

[alapps]

wanyue,

Recovery of the "system.dbf" without a backup is doubtful... However, attempt of "Force" open the database (This works with bad datafiles, system is questionable...)

sqlplus internal/password
STARTUP FORCE;

good luck....

[jmodic]

Originally posted by alapps
Recovery of the "system.dbf" without a backup is doubtful... However, attempt of "Force" open the database (This works with bad datafiles, system is questionable...)

sqlplus internal/password
STARTUP FORCE;

STARTUP FORCE has nothing to do with starting the database with bad datafiles. It starts the database just like normal STARTUP command, so if STARTUP returns errors about corrupted datafiles, so will STARTUP FORCE.

STARTUP FORCE is nothing but the following two commands merged into one:

SHUTDOWN ABORT
STARTUP

[wanyue]

wonder if anyone knows any back door for recovery of this system dbf file?

[marist89]

Originally posted by wanyue
wonder if anyone knows any back door for recovery of this system dbf file?

Restore from backup. If you don't have a backup, rebuild your database.

[Sureshy]

hope you have learnt something from this.

[ramaral]

If you do have something with the system tablespace (or any other tablespaces) that you need to get then do this:

edit the init.ora file and add the following line:

_allow_resetlogs_corruption=true

Startup the database. It will open. Doublecheck on metalink for the specific syntax but I think that is it.


One BIG caveat: only use this to open the database so you can export data that you need for you to be able to rebuild the database. Oracle WILL NOT support you and your database if you use this to open the database for production use.

Oh yes one more thing: please consider a backup strategy. It will make things easier for you. Take it from experience.

Just do one thing though:

Ora 1115 indicates that the file is not accessable. That the device may be offline. Make sure the file system is mounted and available to the oracle user. I had the unix guys work on disk once and mounted them but with root access available and not with oracle access. So double check that first.


[Edited by ramaral on 07-11-2002 at 08:44 AM]

[raghud]

I tried your solution . It is not working for me ..I simulated the problem on my test box . I renamed the system1.dbf to temp.dbf and tried to startup with _allow_resetlogs_corruption=true entry in init.ora ..

ORA-01157: cannot identify/lock data file 1 - see DBWR trace file
ORA-01110: data file 1: 'D:\KELLER\KELLER\SYSTEM01.DBF'