In this Document
Symptoms
Changes
Cause
Solution
References
APPLIES TO:
Oracle Database - Enterprise Edition - Version 10.2.0.4 to 12.2.0.1 [Release 10.2 to 12.2]
Oracle Database Cloud Schema Service - Version N/A and later
Oracle Database Exadata Express Cloud Service - Version N/A and later
Gen 1 Exadata Cloud at Customer (Oracle Exadata Database Cloud Machine) - Version N/A and later
Oracle Cloud Infrastructure - Database Service - Version N/A and later
Linux x86-64
Linux x86
***Checked for relevance on 02-Sep-2016***
Oracle Server Enterprise Edition - Version: 10.2.0.4
10.2.0.4
***Checked for relevance on 26-AUG-2014***
SYMPTOMS
You discover messages of this nature in your alert log:
ORA-27090: Message 27090 not found; product=RDBMS; facility=ORA
Additional information: 3
Additional information: 128
Additional information: 65536
- OR -
ORA-27090: UNABLE TO RESERVE KERNEL RESOURCES FOR ASYNCHRONOUS DISK I/O
Additional information: 3
Additional information: 128
Additional information: 65536
- OR -
ORA-27090: Message 27090 not found; product=RDBMS; facility=ORA
Linux-x86_64 Error: 4: Interrupted system call
Additional information: 3
Additional information: 128
Additional information: 65536
Strace against DBWR shows:
io_setup(4096, 0x66e1588) = -1 EAGAIN (Resource temporarily unavailable),
which is related to "aio-max-nr" kernel limit.
CHANGES
CAUSE
The "aio-max-nr" kernel limit is too low.
SOLUTION
The "aio-max-nr" kernel limit should be adjusted according to Oracle recommendations which are available in this document:
Oracle Validated Configuration:
http://linux.oracle.com/pls/apex/f?p=102:2:2007385298933639::NO::P2_VC_ID:426
Also, this parameter should be set as follows:
-------------------------------------
fs.aio-max-nr= 3145728
-------------------------------------
NOTE:
Per bug Bug 13554729 - CORRECT FS.AIO-MAX-NR = 3145728
The Oracle documentation lists the minimum value as the max value.