Browse Prior Art Database

Simultaneous Time Related Monitoring of Multiple SCSI Buses

IP.com Disclosure Number: IPCOM000110725D
Original Publication Date: 1992-Dec-01
Included in the Prior Art Database: 2005-Mar-25
Document File: 1 page(s) / 51K

Publishing Venue

IBM

Related People

Floryance, GG: AUTHOR

Abstract

A tool to simultaneously monitor, record, and time stamp activity on multiple SCSI buses is disclosed. The data from multiple buses is correlated in time to determine performance characteristics and workloads of SCSI devices and SCSI subsystems. This information is used to define product design points and to optimize the programmable characteristics of installed products.

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Simultaneous Time Related Monitoring of Multiple SCSI Buses

      A tool to simultaneously monitor, record, and time stamp
activity on multiple SCSI buses is disclosed.  The data from multiple
buses is correlated in time to determine performance characteristics
and workloads of SCSI devices and SCSI subsystems.  This information
is used to define product design points and to optimize the
programmable characteristics of installed products.

      The SCSI Bus Snoop card simultaneously monitors and records
SCSI bus events on multiple SCSI buses.  A SCSI bus event generally
begins at Selection or Reselection and completes at BusFree.  The
only exception is linked commands in which the Link Command Complete
message serves to both complete the current event and then
immediately begin a new event.

      Information collected for each event includes the following:
o    Beginning and ending time of the event
o    All message, command, and status bytes
o    A count of the total number of data bytes transferred
o    A variable number of data bytes determined by a programmable
limit

      Multiple Snoop cards are time synchronized to a common clock
derived from the PC bus.  The PC clock rate is divided down on each
card to approximately 1 usec so that the cards can be used in PCs
having a range of clock frequencies.  Thus, the accuracy of the
time-stamping of an event is approximately 1 usec.

      The Snoop card allows programmable selection o...