最近观察到数据库服务器 $BDUMP 目录下频繁出现 Trace 文件,内容大致为:
Warning: lio_listio returned EAGAIN Performance degradation may be seen. Warning: lio_listio returned EAGAIN Performance degradation may be seen. Warning: lio_listio returned EAGAIN
搜索了一下, IBM 给的官方解释为:
If the maxreqs value is too low, then the following Oracle warning message might be returned:
Warning: lio_listio returned EAGAIN.
This warning message indicates a need to increase the maxreqs value. When performing file system I/O, a maxservers value that is too low can also indirectly cause this warning message
同时,建议
maxservers=(10 * number of logical disks / number of processors)
AIO Servers ,指的是处理异步IO请求的核心进程.
关于 AIO Servers , 如果要深究，还有许多内容可以讨论。有时间的话把其他内容补充上来.