Monitoring asynchronous I/O in AIX

Use the following command:

   pstat -a | grep aioserver 
   

You may have to increase the number of aioservers if:

• The actual number of active aioservers is equal to the maxservers and
• The CPU utilization of all the aioservers appear to be even (indicating that all aioservers are used)
• You continue to see the Warning: lio_listio returned EAGAIN messages

The MetaLink Notes discusses the issue and provide recommendations for maxreqs, minservers and maxservers:

• Oracle MetaLink Note:443368.1 - How does Oracle use AIO servers and what determines how many are used?