Configuring aio

  1. create the /dev/async character device
# /sbin/mknod /dev/async c 101 0x0
# chown oracle:dba /dev/async
# chmod 660 /dev/async
  1. configure the async driver in the kernel:
# kcmodule asyncdsk=static

:pushpin: this will require a kernel rebuild and reboot.

  1. set max_async_ports:
# kctune max_async_ports=<value>

max_async_ports limits the maximum number of processes that can concurrently use /dev/async. Set this parameter to the sum of ‘processes’ from init.ora + number of background processes. The background processes started at instance startup will open /dev/async twice.

:pushpin: If max_async_ports is reached, subsequent processes will use synchronous I/O

How to check # ports in use:

# fuser -u /dev/async 2>/dev/null | wc -w
103

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