asynchronous I/O
A type of I/O operation that allows other processing to proceed before the I/O is completed. Also known as non-blocking I/O and abbreviated as AIO. InnoDB uses this type of I/O for certain operations that can run in parallel without affecting the reliability of the database, such as reading pages into the buffer pool that have not actually been requested, but might be needed soon.
Historically, InnoDB has used asynchronous I/O on Windows systems only. Starting with the InnoDB Plugin 1.1, InnoDB uses asynchronous I/O on Linux systems. This change introduces a dependency on libaio. On other Unix-like systems, InnoDB uses synchronous I/O only.
See also buffer pool.
See also non-blocking I/O.