═══ 1. Help for DCAT DCF/2 Compression Analysis Tool ═══ 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 (303) 484 2670, or toll free to our sales order line at (800) 666 4672 and FAX orders to (800) 955 4672. ═══ 1.1. The DCF/2 Big Picture ═══ 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. ═══ 1.2. Details on the DCAT Installation. ═══ 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. ═══ 1.3. Using the DCAT Disk Compression Analysis Tool ═══ 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. ═══ 1.3.1. What/Where to Test ═══ 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. ═══ 1.3.2. Compression Options ═══ 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. ═══ 1.3.3. Display & Logging Setup ═══ 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 !