ORA-15120: ASM file name ‘ORA-27090: Unable to reserve kernel resources f’ does not begin with the ASM prefix character

March 24, 2022 Leave a comment

Problem:

The customer created 36 databases on the same server and while creating the 37th using dbca got the following error:

Reason:

fs.aio-max-nr value was set too low in /etc/sysctl.conf. In general, value 3145728 that was set in their case, suits many environments, but if the number of databases on the server increases then this parameter should be adjusted accordingly.

Solution:

The formula used while calculating the value for this parameter is the following:

aio-max-nr = no of process per DB * no of databases * 4096

In their case, the number of processes per DB was 1000, the number of databases that planned to be created was 80. Based on the above value should be:

aio-max-nr = 327680000
  1. Add/update value in /etc/sysctl.conf:
# vim /etc/sysctl.conf

fs.aio-max-nr = 327680000


2. Run /sbin/sysctl -p to immediately enforce the changes:

# sysctl -p

Delete already created files and recreate the database, it will succeed this time.

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Filed under 12c, 19c, DB Tagged with , , , , ,

Can fs.aio-max-nr be changed on a live system?

December 17, 2021 Leave a comment

Short answer:

Yes, it can be changed without impacting the business operations.
Oracle source: Doc ID 2269728.1
RHEL source: https://access.redhat.com/solutions/437043

========================Additional information========================

Additional explanation, why you may need to change that value.

Problem:

Alert log shows:

ORA-27090: Unable to reserve kernel resources for asynchronous disk I/O
Linux-x86_64 Error: 2: No such file or directory
Additional information: 3
Additional information: 128
Additional information: 139817340277512

Reason:

The problem is caused by a lower than recommended value for aio-max-nr. The current value is 1048576, but recommended is 3145728.

Solution:

Set fs.aio-max-nr to 3145728 in /etc/sysctl.conf. 

# grep fs.aio-max-nr /etc/sysctl.conf
fs.aio-max-nr = 3145728

Make a new value effective:

# sysctl -p  /etc/sysctl.conf

Verify the new value:

# sysctl -a|grep fs.aio-max-nr
fs.aio-max-nr = 3145728

Filed under Linux, Oracle Enterprise Linux, OS Tagged with , , , , ,