ORA-01115 ORA-01110 ORA-27091 ORA-27072 Error: 5: I/O error (Doc ID 559697.1)
In this Document

Symptoms

Changes

Cause

Solution

References

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Applies to: 

Oracle Database - Enterprise Edition - Version 9.2.0.8 and later
IBM AIX on POWER Systems (64-bit)
***Checked for relevance on 16-Feb-2011***

IBM AIX Based Systems (64-bit)

Symptoms

After patching the OS with Patch IBM Technology Level 6 (5300-06) or Level 7 (5300-07), the application log started reporting the following errors:

ORA-01115: IO error reading block from file (block # )
ORA-01110: data file :
ORA-27091: skgfqio: unable to queue I/O
ORA-27072: skgfdisp: I/O error
IBM AIX RISC System/6000 Error: 5: I/O error

- The errors are not reported in the alert log file.
- Running dbv against datafiles from the error messages shows no errors.
- All the mandatory OS patches are applied.
- Oracle patch for Bug 5496862 - IO READING PROBLEMS AFTER INSTALLING IBM TECHNOLOGY LEVEL 5 (5300-05) was installed before patching the OS.

Changes

Patch IBM Technology Level 6 (5300-06) or higher was applied to the OS.

Cause

The value of maxreqs (4096) was too low. This asynchronous I/O parameter specifies the maximum number of asynchronous I/O requests that can be outstanding at any one time and has as default value 4096.

Solution

Increase maxreqs to a value greater than or equal to 8192.

Steps:
1. run aioo -a command to double check current setting for aio0 device 
2. run aioo -o maxreqs= to set maxreqs dynamically 
3. chdev -l aio0 -a maxreqs= -P to set the value of maxreqs permanently for next reboot
4. run aioo -a to confirm change 
5. restart oracle

NOTE: Values that fixed the errors: 8192, 16384 or 32768.

References

BUG:5496862 - IO READING PROBLEMS AFTER INSTALLING IBM TECHNOLOGY LEVEL 5 (5300-05)
NOTE:390656.1 - IO Interoperability Issue between IBM ML05 and Oracle Databases
NOTE:395375.1 - Opatch Fails With Error Code 73 and 'ar: 0707-126' When Applying Interim Patch 5496862
NOTE:418105.1 - Is Patch 5496862 Mandatory for 10.2.0.3?
NOTE:430697.1 - 'Warning: lio_listio returned EAGAIN' On ASM
NOTE:443944.1 - Is Patch 5496862 applicable on AIX 5.3 TL 06 and higher AIX 5.3 TL's ?
NOTE:5496862.8 - Bug 5496862 - AIX: Mandatory patch to use Oracle with IBM Technology Level 5 (5300-5)