aio(F)


aio -- asynchronous I/O tunable parameters

Description

The Asynchronous I/O (AIO) facility is an installable package typically used by special purpose applications, such as database servers. There are a set of parameters in the mtune file associated with AIO; if necessary (for example, console messages indicate running out of AIO resources), these can be altered by using idtune(ADM). The major tunable parameters are as follows:

NAIOPROC
The number of processes which may be simultaneously doing AIO. The default value is 5.

NAIOREQ
The maximum number of pending AIO requests. The default value is 120.

NAIOREQPP
The maximum number of AIO requests that a single process can have pending. The default value is 120, meaning that one process can potentially exhaust all AIO resources.

The AIO tunable parameters that follow are unlikely to need changing, but are documented here for completeness:


NAIOBUF
The number of AIO buffers. In the current implementation, this should always be set to the same value as NAIOREQ.

NAIOHBUF
The number of AIO hash queues (internal).

NAIOLOCKTBL
Number of entries in the internal kernel table for AIO lock permissions. The default value is 10. If there are many entries in the /usr/lib/aiomemlock file, this number might need to be increased.

Note that in order to use the AIO facility, the system administrator must configure it into the system using mkdev aio. See mkdev(ADM) for further details.

Files


/usr/include/sys/async.h
definitions for asynchronous I/O

/usr/lib/aiomemlock
permissions file to control how much memory can be locked by whom

/etc/aiolkinit
command to lock physical memory for AIO transfers

/usr/bin/aioinfo
command to print statistics on AIO usage

See also

aio(F), aio(HW), aioinfo(ADM), aiolkinit(ADM), aiomemlock(F), idtune(ADM), mkdev(ADM), mtune(F), stune(F)
© 2005 The SCO Group, Inc. All rights reserved.
SCO OpenServer Release 6.0.0 -- 03 June 2005