CD Ware Multimedia 1994 November/Cd Ware (Nro. 2) - Epimundo.iso/OS2/DCF211B.ZIP/DCAT.HLP

OS/2 Help File | 1993-10-24 | 25.2 KB | 255 lines

ΓòÉΓòÉΓòÉ 1. Help for DCAT DCF/2 Compression Analysis Tool ΓòÉΓòÉΓòÉ

Welcome to the DCAT Version 1

If this is your first time using the DCAT, it will automatically enter
installation mode.  The installation involves selecting a target disk to place
the DCAT program files and restarting your system so that the DCF/2
compression/decompression engine (CDE) device is started.

We recommend that you spend a few minutes flipping through this help facility
to get a feeling for the DCAT program features.

If you already have the DCF/2 installed, the DCAT can be installed in the same
directory without conflicts.

To view additional help, select one of the following topics:

     o The DCF/2 Big Picture
     o Details on Installation
     o Using the DCAT Disk Compression Analysis Tool

 This utility is available to everyone interested in the DCF/2 program and its
 capabilities.  Thank you for your interest in our products.

 If you do not already have the DCF/2 and you require additional product or
 sales information, please call our sales hotline at US area code (303) 484
 2665, FAX at [phone], or toll free to our sales order line at (800) 666
 4672 and FAX orders to [phone].


ΓòÉΓòÉΓòÉ 1.1. The DCF/2 Big Picture ΓòÉΓòÉΓòÉ

The DCF/2 is an on-the-fly disk compression facility for all OS/2 file systems.
Transparent to all standard DOS, Windows, and OS/2 applications software, the
DCF/2 works with all existing disk structures - NO repartitioning of your
existing system is needed.

The DCF/2 is a full 32-bit program system which requires IBM's OS/2 2.0 or
later.  All OS/2 file systems are supported as host storage for DCF/2 virtual
disk units.

The DCF/2 is a system of building blocks designed to grow with your entire
operating environment - IBM's OS/2 2.0 32-bit multitasking makes it all
possible!

The following architecture diagram of the DCF/2 details these building blocks.

                             The DCF/2 Architecture

The DCF/2 is designed with each element externalized;  third-party developers
can add compression, encryption, and other disk related capabilities to your
system environment (contact the PSC technology lab for pricing and details of
the DCF/2 CDE API kit).

When the OS/2 operating system or an application program requests disk
accesses, the DCF/2 Physical Device Driver (PDD) receives the request and
repackages it for processing by the Ancillary Control Process (ACP).  The ACP
is a standard, high-level software layer which shuffles the compressed disk
request between Compression/Decompression Engines (CDE's), Input/Output Engines
(IOE's), and physical disk structures.

The ACP compressed disk requests are processed and managed by standard OS/2
disk and file services.  The DCF/2 can use all logical media, such as hard disk
drives, LAN network drives, and removable media like floppies.  This
architecture guarantees compatibility with all OS/2 system and application
software updates.

The DCF/2 benefits from all OS/2 file and memory management features, so that
applications 'see' the DCF/2 VDU as a "real" disk.

The DCF/2 takes advantage of the OS/2 High Performance File System, allowing
DCF/2 VDU's to support all of its advanced features like 255 character file
names, integrated extended attributes, and HUGE disk support.


ΓòÉΓòÉΓòÉ 1.2. Details on the DCAT Installation. ΓòÉΓòÉΓòÉ

The DCAT installation process simply copies the DCAT program files to a Target
Disk of your choice and sets up your configuration statements to load the DCAT
device driver during the next reboot.  The installation then offers to restart
your system for you.

The only installation option you need to enter is the Target drive where you
want the DCAT program files installed.  This will create or use the
subdirectory \DCF2 to store the program files.

Select the Target Drive by using the Target Drive spin button.  Only logical
disk units are presented in the Target Drive spin button selection box.

When you have completed the DCAT installation, you will have the option of
installing the DCAT desktop icon and restarting your system.  You can install
the DCAT desktop icon to more easily start the DCAT.  You will need to restart
your system before the DCAT program is available.


ΓòÉΓòÉΓòÉ 1.3. Using the DCAT Disk Compression Analysis Tool ΓòÉΓòÉΓòÉ

The DCAT helps you to measure the value of the DCF/2 for your system
environment.  The DCAT tests compression and decompression engine performance
for all OS/2 2.1 system environments.  In addition, the DCAT offers you a
unique tool to analyze the behaviour of your disk and your computer's
performance (independent of compression).

The DCAT can test WHOLE physical disk units (PDUs) or logical disk units (LDUs)
based on files and directories.

The DCAT main dialog screen displays your current DCAT status on the left and
center of the screen.  The first line describes the kind of test to be
performed and the sampling rate.  The next line shows exactly what is to be
tested.  For example, this line will show the disk and list of files to be
analyzed if file-by-file.

The next two lines indicate the type of test to be performed, what compression
options, if any, and what devices are to be used, if any.

The next two lines show how the test results are to be displayed and/or logged
to a test logfile.

Under the 'Current Data Stream Statistical Sample' is an entry line where the
current test status (file, compression indicator, or status line) will appear.

The following eight fields (two columns of 4 entry boxes) are where the test
results are displayed.

Tab to one of the following additional help panels to see details on the
various DCAT setup options:

     o What/Where to Test
     o Compression Options
     o Display & Logging Setup

 The What/Where to Test allows you to specify whether the test is to be
 performed on a complete physical volume or a logical set of files, the number
 of statistical samples to be made during the test, and what files (if
 file-by-file) to be used.

 The Compression Options allows you to specify the base compression to be used
 for the test, the compression priority, and other compression specifics.

 The DCAT Display and Logging Setup section allows you to set the run-time
 process priority of the DCAT, the refresh rate of the DCAT control dialog, and
 a checkbox to determine whether logging messages are written to the DCAT.LOG
 data file.

 The DCAT outputs statistics for each test on a refresh-rate basis as set in
 the Display & Logging Setup section.  The ACR, or Average Compression Ratio,
 is the ratio of decompressed bytes to compressed bytes.

 The Compression Engine Hits field describes the number of times the DCAT
 program has to ask the DCF/2 CDE (Compression/Decompression Engine) to perform
 a compression function.

 The Elapsed Time registers the number of seconds elapsed since the start of
 the last test.

 The CPU Performance Indicator is a relative measure of information processed
 per second of test.  This is a useful measure when comparing two different
 computers processing identical data or the same computer using different cache
 setups.

 The Total Bytes Read and the Recoverable Bytes Using DCF/2 are indications of
 how much of the disk has been written and how much physical disk space would
 be returned if you were compressing this same data using the DCF/2.  This is
 "hard" information -- that is to say the recoverable bytes are the actual
 bytes which you would/will recover by using the DCF/2 data compression
 product.

 The cumulative bytes sampled and cumulative bytes read are the basis for all
 of the other information.  The cumulative bytes sampled are the bytes read and
 compressed.  The cumulative bytes comressed are the the results of those
 compression tests.


ΓòÉΓòÉΓòÉ 1.3.1. What/Where to Test ΓòÉΓòÉΓòÉ

The What/Where to Test options button brings up a dialog screen where you can
enter which drive you want to test and how you want to test it.

You can select the drive letter to be tested using the spin button labeled
Physical Disk to be Tested.

Testing of the physical disk will either be file-by-file or by using raw sector
reads.  In either case, you can select a statistical sampling rate. This allows
you to speed up you test.

On the lower half of this page you will select either "Perform Compression on
Whole Physical Disk Unit" or "Perform Compression Test File-by-File".  Since
the DCF/2 performs compression operations on pure "chunks" of data as requested
by the operating system during normal operations, you will get the most
accurate results from measuring a totally full physical volume by testing the
whole PDU.  Unfortunately, most volumes are not completely full or they don't
necessarily contain only information to be compressed, so most users like to
measure their disk/compression returns on a file-by-file basis.

File-by-File testing is done on a simple, recursive find-first, find-next
basis.  You can elect to perform tests for a simple, single directory (or file
for that matter) or a complex tree search of all files on a disk.

The DCAT file parser allows full wildcard specifications ("*", "?") and long
filenaming.


ΓòÉΓòÉΓòÉ 1.3.2. Compression Options ΓòÉΓòÉΓòÉ

The DCAT Compression Setup section allows you to select Base Compression,
Compression Priority, and whether to sample files or process them entirely.

The Base Compression options allow you to measure compression results based on
Zero Compression, Compress Only, Compress and Decompress, and Compress,
Decomress, and Verify.

The Zero Compress option allows you to measure test times without the CDE
compression load.

The Compress Only option says to compress each sample, but not to decompress
it.  This is the fastest compression test.

The Compress and Decompress test calculates the time needed to perform both a
compress and a decompress on each chunk.  The decompress time is typically less
that 10% of the compression time.

The Compress, Decompress, and Verify test verifies that the compressed chunk is
the same as the uncompressed original chunk.

Compression can be prioritized based on Compression, Speed, or a Balance
between both Speed and Compression.

Hybrid compressions are used for special compression cases (such as when a disk
is initially formatted).

File-by-File tests can be performed by sampling only one chunk (32K normally)
or processing the entire file.  Statistical measurements are significantly
faster than whole file tests and are generally close to reality.


ΓòÉΓòÉΓòÉ 1.3.3. Display & Logging Setup ΓòÉΓòÉΓòÉ

The DCAT process is a standard OS/2 ring 3 application.  If you want to start a
DCAT test and continue working on another job, you will want to set the job
priority to 1.  Priority of 1 is idle-time, 2 is normal, 3 is time critical,
and 4 is server.

The DCAT Display Refresh Rate is the number of seconds between updates to the
DCAT Test Dialog box statistics.  The statistics are accumulated in the
background and this option controls the frequency at which the screen is
updated with those statistics.

The Log Statistics to DCAT Logfile checkbox determines whether a logfile named
DCAT.LOG is maintained with the results of each test.  If checked, the logfile
will reflect a history of each test run, including the starting statistics (if
not reset) and the results at test termination.

The option to log file names (and sizes) can generate lots of information very
quickly and will definitely slow down tests.  USE WITH CAUTION !