Browse Prior Art Database

Switch-Based Access Control in a Closely Coupled System

IP.com Disclosure Number: IPCOM000101065D
Original Publication Date: 1990-Jun-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 2 page(s) / 72K

Publishing Venue

IBM

Related People

Cheng, T: AUTHOR [+2]

Abstract

Disclosed is a method for achieving fast access to shared data in a multiprocessor system with a central switch.

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

Switch-Based Access Control in a Closely Coupled System

       Disclosed is a method for achieving fast access to shared
data in a multiprocessor system with a central switch.

      The method applies to the environment shown in the figure,
where a number of processors are coupled through a high-speed switch
in a switched-star topology.  All shared data reside in one or more
storage subsystems connected to the switch.  Every access to shared
data from a processor is performed via the switch. Access to the
shared data is controlled by an access-control mechanism.

      In the conventional approach with separate access-control and
switch units, access to a shared file or record in the data storage
consists of at least two steps:
1.  Communication to perform the access-control protocol.
2.  Communication to access the shared data.

      Each of the above steps involves a two-way communication
session through the switch.  These two steps need to be performed in
a strictly serial fashion. When the systems are located physically
far apart, the round-trip delays involved in the communication
sessions are considerable and therefore influence the overall
performance significantly. The performance can be improved by
combining the two steps into one, that is by performing the
access-control protocol as part of an access.

      The method is illustrated in the figure.  The processors are
coupled through a high-speed switch to a number of storage modules
via high-speed fiber-optic links. The access-control function resides
within the switch. Access to shared data is accomplished as f...