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Don Burleson Blog 







Oracle startup I/O error

Oracle Database Tips by Donald BurlesonJanuary 9, 2015

Question:  I am getting an I/O error at database startup time:

SQL> startup

ORACLE instance started.

ORA-00221: error on write to control file
ORA-00206: error in writing (block 1, # blocks 1) of control file
ORA-00202: control file: '/U02/database/mydb/control01.ctl'
ORA-27072: File I/O error
Linux Error: 11: Resource temporarily unavailable


Thread 1 advanced to log sequence 7268
Errors in file /oracle/product/10.2.0/db_1/admin/alpaorcl/bdump/alpaorcl_arc1_25850.trc:
ORA-00202: control file: '/home/logdisk2/oradata/alpaorcl/control03.ctl'
ORA-27091: unable to queue I/O
ORA-27072: File I/O error
Linux-x86_64 Error: 5: Input/output error

Is this just a I/O error con the controlfile, or do I have a real disk failure?

Answer:  Your first step is to ensure that you have a "real" disk I/O error, and not a phantom I/O error, and the OS logs will provide this information. 

I would start by seeing if the controlfile is really corrupt.  I would start by seeing if you can issue the UNIX "view" or "strings" command on the controlfile, and check your OS syslog for file I/O errors. 

Basically you need to have your SYSADMIN staff call you DASD vendor to come and replace your damaged media.

Next, I would take one of the other copies of your control file and replace the one referenced in your startup.  If you have not multiplexed your controlfiles, you will have made a daily backup of your controlfile that you can grab from the trace file.
alter database backup controlfile to trace;

Normally, all I/O errors are quite serious, and you need to open an SR with Oracle technical support. 

The remedy for a disk I/O error at startup is to open an SR, restore the disk to a working device, and restore the database using RMAN.  Oracle tech support may advise you to employ hidden recovery parameters.


If you like Oracle tuning, you may enjoy my bestselling book Oracle Tuning: The Definitive Reference", with over 900 pages of BC's favorite tuning tips & scripts. 

You can buy it direct from the publisher for 30%-off and get instant access to the code depot of Oracle tuning scripts.



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