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

Short answer:

Yes, it can be changed without impacting the business operations.
Oracle source: Doc ID 2269728.1
RHEL source:

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

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


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


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


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