SCSI Bus Performance Monitor

See an image of the master
Master Module shown


General Description :

The SCSI-PMON is a family of low cost performance monitors for the SCSI bus.

Being plugged onto the cable like a normal device they monitor the usage of the bus and report statistics to a host every second via a serial connection. Up to more than a hundred slave devices can be daisy chained to a master module allowing synchronized readings on many busses. This feature is particulary useful for the modern RAID controllers to monitor the output busses and the input bus concurrently. By this the system manager gets valuable information about the real load on the SCSI-busses; information that before could be gathered with expensive and hard to use SCSI-Analyzers only.


This family consists of devices for single-ended/differential busses, each with a variety of connectors. All of them can be used on 8 or 16 bit, fast and ultra-fast busses. They measure the times a bus spends in what kind of phase, grouped into 4 categories: FREE, OVERHEAD, DATA IN and DATA OUT. This data (in percent of a second) together with the number of the bus is sent to a host (PC or other computer with a serial line) every second in ASCII format.


The SCSI-PMON-D family will report the figures in terms of transfers per second plus operations per second.

Both families use a master/slave concept where one master module provides all the timing and control for all the slaves. The master also reads all the slaves, converts their raw (binary) data to ASCII and sends it via a UART to the host. Each slave monitors one bus and measures the four key parameters of it. To ease the usage each master module houses one (the first) slave in the same box.

Technical Data : SCSI-PMON-T Common Data
  Sample interval 153ns
  Report format percent of one second, ASCII
  Serial line 9600 Baud, 8 bit, no parity, 1 stop bit
  Cascadability >16 devices (except - SA devices)
  Bus speeds FAST, ULTRA-FAST
  Bus widths 8/16 bit
  Used device ID none (absolutly passive on SCSI bus)

The basic core module gets a bus specific buffer interface to adapt to the single-ended or differential version of the SCSI-bus. There are modules that are connected to the bus like a device or are inserted into the cable. All types of slave modules can be combined with all other types of slaves (of the same family e.g. SCSI-PMON-T) and with all master modules of the same family.

Price and Availability :

For pricing information please contact our partner Onsite Computer. In addition to selling the hardware they provide the software for a variety of hosts (UNIX, Windows NT, ...)

© Paul Elektronik, 1998-2002