Browse Prior Art Database

SCSI Mode Data Selection Algorithm

IP.com Disclosure Number: IPCOM000122558D
Original Publication Date: 1991-Dec-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 2 page(s) / 83K

Publishing Venue

IBM

Related People

Schwendiman, CA: AUTHOR [+2]

Abstract

Disclosed is an algorithm to dynamically detect and select mode parameters supported by a wide range of SCSI (Small Computer System Interface) devices with considerable ease and efficiency.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

SCSI Mode Data Selection Algorithm

      Disclosed is an algorithm to dynamically detect and
select mode parameters supported by a wide range of SCSI (Small
Computer System Interface) devices with considerable ease and
efficiency.

      There are no doubt numerous algorithms existing to accomplish
this task.  The purpose of the SCSI Mode Sense and Mode Select
commands are well known in the art.  The SCSI Mode Sense command
provides the capability to request the changeable parameters for a
given SCSI device and to request the current parameters for a given
SCSI device. An implementer is expected to perform these mode sense
commands to detect what he can and needs to change.  This is where
the innovation of the implementer comes in to play as to how he
performs the task of detection and selection. Many algorithms can be
imagined ranging from byte comparison to bit shifting, etc.; however,
in many instances devices are force-fed predefined mode select
parameters without doing any detection and selection.  Another
alternative is to not do any setting of mode parameters and force
devices to operate with their default settings.  Such settings are
not always optimum for all using systems depending on the performance
and data integrity characteristics of each host system.

      The algorithm disclosed consists of two routines.  One routine
formats a variable length array of mode data into a consistent
understandable format. This routine parses the buffer of mode data
and stores the index to each supported page in a separate...