Browse Prior Art Database

Reliability, Availability, Servicability Daemon

IP.com Disclosure Number: IPCOM000121943D
Original Publication Date: 1991-Oct-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 2 page(s) / 66K

Publishing Venue

IBM

Related People

Arndt, RL: AUTHOR [+2]

Abstract

This article describes the use of a daemon (UNIX* background process) to provide additional function to a UNIX device driver that would otherwise not be possible. The additional functions provided enhance the reliability, availability, and servicability of a device.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 65% of the total text.

Reliability, Availability, Servicability Daemon

      This article describes the use of a daemon (UNIX*
background process) to provide additional function to a UNIX device
driver that would otherwise not be possible.  The additional
functions provided enhance the reliability, availability, and
servicability of a device.

      UNIX device drivers and kernel extensions are limited in their
access to filesystems and system services, due to their execution
environment.  Unlike application programs, device drivers and kernel
extensions execute primarily on the interrupt level, with no access
to normal system information, services, or filesystems.  However, the
use of a daemon in conjunction with a device driver provides the
capability for a device driver to initiate the execution of system
and application level tasks.

      The daemon process is created upon detection and configuration
of the device, and executes in the UNIX operating system environment
as a background process.  The daemon's primary responsibility is to
"sleep", waiting for signals from the device driver, and to process
the signals as they arrive.  The specific events posted to the daemon
depend on the characteristics of the device, but following is an
example use of a daemon in conjunction with a DASD (Direct Access
Storage Device) subsystem device driver.

      Consider a DASD subsystem made up of a host I/O bus adapter,
DASD controllers, and DASD, each of which contain downloadable
mic...