AIO on AIX 6.1

juredd1 · September 16, 2011, 11:21am

I understand that AIO is not something that you turn on in AIX 6.1 but I am getting a request to turn on posix aio. I am guessing a value of 0 means it's off but not sure.

root@foobar:/> ioo -a | grep active
                    aio_active = 1
                    posix_aio_active = 0

When I try to change the value to 1 I get an error basically that says it can't be changed.

From my understanding his application is trying to run an lsattr command to see if AIO is turned on which won't work because that don't work in AIX 6.1.

I found a technote on the IBM site where someone had problem with DB2 9.1 and a fix was available to resolve this issue for DB2. The product currently trying to be installed is SAP.

Thanks for any insight you can provide.

zxmaus · September 17, 2011, 10:22pm

Hi

AIO subsystems are in 6.1 and later loaded by default and not activated. They are automatically started at the time when the application initiates the AIO I/O requests, aio_active and posix_aix_active can only be changed by AIX, and they are set to 1 only when AIO kernel extensors are used and pinned - in other words if the application is actively trying to use it. When in your case posix is off, than the application doesnt want to use it. The tunables fastpath and fsfastpath are now restricted tunables and set to 1 by default.
Hope this helps,
regards
zxmaus