SCSI_Inspector.app - A tool for examining and benchmarking SCSI devices under NeXTSTEP 3.2 on both Motorola and Intel hardware. Software, Documentation and Source Code Copyright 1994, Christopher A. Wolf INTRODUCTION ------------ SCSI_Inspector.app is a NeXTSTEP application which provides extensive technical information about any SCSI peripherals which are attached to the computer. In addition to displaying device specifications and parameters, SCSI_Inspector.app can also perform benchmarking and simple diagnostic functions. All of these features are accessible through the easy to use NeXTSTEP graphical user interface. SCSI_Inspector.app is distributed as a FAT binary which uses the SCSI2_Kit to provide architecture independent SCSI functionality on both Intel and Motorola NEXTSTEP 3.2 systems. The current version of SCSI_Inspector is a beta test version which is still under development and portions of it have not been exhaustively tested on all possible hardware configurations. Please exercise caution when using this tools and, as always, be sure to keep current back-ups of all your important data. Complete (but at this time sparsely commented) source code for SCSI_Inspector.app is provided. LEGAL ----- The software, documentation and source code for SCSI_Inspector.app are provided as a part of SCSI2_ToolBox and are Copyright 1994, Christopher A. Wolf. Portions of the source code and documentation of this application are directly derived from source code and documentation included with an earlier work, SCSI_Inquirer.app, Copyright 1990, 1991, 1992 by Jiro Karen Nakamura and Focal Point Computer. In personal e-mail dated July 1, 1994, Jiro Karen Nakamura <jn19@cornell.edu> stated that she is no longer actively developing or supporting SCSI_Inquirer and granted me permission to assume responsibility for its continued development and maintenance. In personal e-mail dated July 2, 1994, Jiro Nakamura provided the following statement releasing previous distribution restrictions on her work: > Focal Point Computer, Inc. has transferred all rights to SCSI Inquirer > to Jiro Nakamura. Jiro Nakamura allows both the source code and object > code of SCSI Inquirer to be used as learning tools on the NeXTSTEP > computer. They may be freely distributed and modified so long as no > attempt at profit is made. If you want to go through the minor steps > to make SCSI Inquirer a Free Software Foundation GNU program, I give > you my blessing... In accordance with these terms the components of SCSI2_ToolBox are distributed under the GNU Public Licenses. SCSI_Inspector.app is distributed under the GNU General Public License, whose complete text can be found in this archive in the file SCSI_Inspector/Documentation/COPYING. SCSI2_ToolBox is distributed under the Library GNU Public License, whose complete text can be found in this archive in the file SCSI2_Kit/Documentation/COPYING. This software and documentation is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. INSTALLING SCSI_INSPECTOR ------------------------- Unpack the SCSI2_ToolBox.tgz archive and use the Workspace Manager to copy SCSI_Inspector.app (in the SCSI_Inspector directory) to its destination directory on your system. SCSI_Inspector.app must be run as root in order to perform the low level SCSI device driver access which it depends on. If you try running SCSI_Inspector.app without root privileges it will display a panel informing you that it must be run as root and then exit. Therefore, the first time you run SCSI_Inspector.app you must either be logged in as root or use "Open Sesame" to launch it. Once you have SCSI_Inspector.app running you can use the "Install SET-UID root" option of the "Tools" menu to tell it to install itself SUID root. If the application is already installed SUID root this menu option will be disabled. Installing this or any other application SUID root allows anyone to run the program as if they were root and could be a potential security problem. USING SCSI_INSPECTOR -------------------- Once SCSI_Inspector.app is started it displays a panel entitled "SCSI Selector" with a scroll view displaying the manufacturer and model number of any peripherals attached to the SCSI bus at IDs (targets) 0 through 7. "No Device" will be displayed at SCSI IDs which do not have a device attached. The SCSI host adapter is usually configured as ID 7 but will not be listed in the "SCSI Selector" window since it is not a peripheral device. Click once with the left mouse button on a device name to bring up the Inspector window for that device. The Inspector window is divided into three sections. The uppermost section contains a pop up menu where the mode of the inspector can be selected. Some or all items in the mode selection pop up menu may be disabled depending on what type of device is selected. The middle section contains information about the manufacturer, model number and SCSI ID (target number) of the selected device. The bottom section is a scroll-view displaying Rich Text information. The mode selection for the inspector controls the type of information that is displayed here. In "Information" mode the Inspector window uses SCSI Inquire and Mode Sense commands to retrieve technical information about the SCSI device that is attached at this ID. This is the default mode when the Inspector window is first opened or when a new device is chosen from the Selector window. The exact information that is displayed varies depending on the type of device that is being queried. The displayed data usually includes such information as the device type, manufacturer, model, revision number, supported standards and feature sets, and media characteristics such as geometry, capacity and density. Most data is interpreted from its original form as raw numerical values and is instead displayed in an easy to read textual format. However some of the information is of a technical nature and explaining the exact meaning of all of the various parameters is beyond the scope of this document. Please refer to your local SCSI wizard or the SCSI 2 standard, a draft copy of which should have been included in the SCSI2_ToolBox archive, for help interpreting any of the more arcane informational messages. In "Diagnostic" mode the Inspector window performs some simple non-destructive diagnostic tests on the selected SCSI device. Currently the tests only check to see if the unit returns "ready" and ask the unit to go through its self-check procedure. This does not tell you much beyond the fact that the device is alive and communicating but hopefully this section will be expanded in the future. In "Benchmark" mode the Inspector window performs a series of non-destructive benchmark tests. This item is only enabled for direct access devices such as disks and CD-ROMs, no provision is currently made for benchmarking sequential access devices such as tape drives. The benchmark is a low-level benchmark which accesses the device driver directly. This means that the benchmark is limited to testing the speed of read accesses and cannot test write accesses since this would result in file system corruption. The benchmark tests read speed using a variety of different block sizes and performs 64 iterations at each block size. The results are reported in a table showing transfer rate in megabytes/second (1 megabyte = 1024*1024 bytes) for each block size. The larger the block size the higher the reported transfer rate since large continuous reads are faster because there are fewer seeks per megabyte of data transferred. Unfortunately, most real world applications and file systems use small block sizes. The complete test is repeated twice. The first time random starting points scattered across the entire disk are used. This test is designed to almost entirely negate the effects of cache (whether it be in main RAM, on the host adapter, or on the drive itself) and thus measures the transfer rate that the drive itself is able to achieve when forced to physically read from its media. The second test repeatedly reads the same set of sectors so that the data is coming almost entirely from cache and thus measures the transfer rate from whatever cache is present. Results for the second test are usually much higher than the first and are limited mostly by CPU speed and memory bandwidth (if the cache is in system RAM), bus-speed (if the cache is on the drive or host-adapter) and driver overhead. Note that for large block sizes the amount of data being read might exceed the cache capacity and thus transfer rates may actually be slower for large block sizes. Since this is a relatively low-level benchmark file system overhead and other file system artifacts (fragmentation, etc.) do not distort the results. However please remember that there are still many factors which can influence even a low-level benchmark such as this one. Processor speed, system memory, bus type, controller, host adapter, system load and drive model are just some of the variables which may influence the result. To obtain the most repeatable measurements the benchmark should be performed at a time when no other disk-access is occurring, when no other CPU intensive tasks are running, and on a machine with enough RAM that no swapping is required to load and run the benchmark program itself. Even when these precautions are followed, in order to meaningfully compare any one of the variables mentioned above (such as disk model) every attempt must be made to keep the other variables (processor speed, controller, bus, host adapter) constant. NOTE: The application is not currently multi-threaded so once a mode selection is made the interface may appear to freeze for a period of time while the program interacts with the SCSI peripheral. This is most noticeable when "Benchmark" mode is selected as it might take several minutes to complete benchmarking functions on some peripherals. The drive activity light should provide an indicator that the application is still working and has not hung. I intend to make the application multi-threaded and correct this problem as soon as possible. BUILDING SCSI_INSPECTOR ----------------------- Complete sources for SCSI_Inspector are provided in case you want to re-build the application and as an example of how to use the SCSI2_Kit. The application should build without modification from the PB.project icon in the SCSI_Inspector directory on either Motorola or Intel hardware. No attempt has been made to build it on HP hardware - if anyone succeeds in getting it to work on HP I would be interested in hearing what you had to do to make it work. If you are having problems getting it to build on Motorola or Intel hardware there are a couple of things to check. First, make sure that the link SCSI2_ToolBox/SCSI_Inspector/Source/SCSI2_Kit.subproj exists and points to the SCSI2_ToolBox/SCSI2_Kit/Source directory. Second, you might want to make sure that all the dependencies are correct... there should be a Makefile.dependencies file in the SCSI_Inspector/Source directory. If there is not you may have to regenerate it using the "make depend" option of Project Builder. (In order to get "make depend" to work on my system I have to select either Intel or Motorola binaries... once the dependency file has been generated I can enable multi-archive binary generation and everything works ok. I don't know if this is a bug in Project Builder or something that I am doing wrong.) Note that the new .app is generated in the SCSI2_ToolBox/SCSI_Inspector/Source directory... it will not over-write the original .app contained in the SCSI2_ToolBox/SCSI_Inspector directory. Also, please note that the makefile.postamble has had several additional targets added to it: RCS::, distribution:: and listing:: which will probably not work on any systems except my own. These targets are involved with project maintenance though and are not necessary to successfully build the app. If you perform the build the completed .app will be placed in the SCSI2_ToolBox/SCSI_Inspector/Source directory to avoid over-writing the original pre-compiled app in the SCSI2_ToolBox/SCSI_Inspector directory. DISTRIBUTION AND FEEDBACK CHANNELS ---------------------------------- SCSI_Inspector.app is available as part of the SCSI2_ToolBox which can be retrieved via ftp from the NEXTSTEP archive on cs.orst.edu. New versions of SCSI2_ToolBox will be uploaded to the /pub/next/submissions directory but will probably be quickly moved to a more permanent home by the archive maintainer. New versions of SCSI2_ToolBox will be announced on the Usenet newsgroup comp.sys.next.announce when they are available. Bug-reports, comments, suggestions, and feature requests can be sent via e-mail to chris@alchemy.geo.cornell.edu. (NeXTmail accepted and preferred.) This is my first publicly released complete NEXTSTEP application so any and all feedback will be appreciated. Please be sure to read all provided documentation and check the TODO files before complaining about broken or missing features though. Also, when providing feedback please specify exactly which revision of SCSI_Inspector you were using. Revision information can be found in the info panel of the app. Thanks! Sincerely, Christopher Wolf ($Id: README,v 0.3 94/09/09 23:28:06 chris Exp Locker: chris $)
These are the contents of the former NiCE NeXT User Group NeXTSTEP/OpenStep software archive, currently hosted by Netfuture.ch.