Disk I/O virtual processors

The following classes of virtual processors perform disk I/O: PIO (physical-log I/O), LIO (logical-log I/O), AIO (asynchronous I/O), and CPU (kernel-asynchronous I/O).

The PIO class performs all I/O to the physical-log file, and the LIO class performs all I/O to the logical-log files, unless those files are in raw disk space and the database server has implemented KAIO.

On operating systems that do not support KAIO, the database server uses the AIO class of virtual processors to perform database I/O that is not related to physical or logical logging.

The database server uses the CPU class to perform KAIO when it is available on a platform. If the database server implements KAIO, a KAIO thread performs all I/O to raw disk space, including I/O to the physical and logical logs.

UNIX only: To find out if your UNIX platform supports KAIO, see the machine notes file.
Windows only: Windows supports KAIO.

For more information about nonlogging I/O, see Asynchronous I/O.


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