ORA-27090 Unable to Reserve Kernel Resources Error

Mehmet Salih Deveci

5 years ago

I got ” ORA-27090 Unable to Reserve Kernel Resources Error ” error in Oracle database.

ORA-27090 Unable to Reserve Kernel Resources Error

Details of error are as follows.

ORA-27090: Unable to reserve kernel resources for asynchronous disk I/O

Cause: The system call to reserve kernel resources for asynchronous I/O has failed.

Action: Check errno

Unable to reserve kernel resources for asynchronous disk I/O

This ORA-27090 is related with the system call to reserve kernel resources for asynchronous I/O has failed.

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.

The “aio-max-nr” kernel limit is too low.

The “aio-max-nr” kernel limit should be adjusted according to Oracle recommendations which are available in this document:

Also, this parameter should be set as follows:
————————————-
fs.aio-max-nr= 3145728
————————————-

Per bug Bug 13554729 – CORRECT FS.AIO-MAX-NR = 3145728

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