***************************************************************************** WINNT.TXT ***************************************************************************** Installation Guide for the LSI Logic SDMS Drivers: SYMC8XX.SYS V4.16.00 SYM_HI.SYS V4.16.00 SYM_U3.SYS V5.09.00 This file describes the features and use of the LSI Logic SDMS device drivers for the Windows NT 4.0 operating system environment. LSI Logic uses the same filenames for their drivers for different Windows operating systems. The driver files are packaged either in separate subdirectories based on the Windows operating system or on different flex disks. To determine the driver file for Windows NT 4.0, note that the filename ends with ".sys". For example, SYMC8XX.SYS. (The same is true for Windows 2000.) To determine the operating system version, go into Windows Explorer, display the driver file, right click on the filename, click on Properties, click on the Version tab. Finally, click on the Internal Filename in the lower section. For Windows NT 4.0, the filename appears as filename (NT 4.0). For example, SYMC8XX.SYS (NT 4.0). This file contains these sections: Introduction for Windows NT 4.0 Features LSI Logic Devices Supported Description Installing the SYMC8XX.SYS/SYM_HI.SYS/SYM_U3.SYS Driver(s) New System Installation CD-ROM Installation Boot Floppy Disk Installation Existing System Installation Windows NT 4.0 Performance Tuning for NT 4.0 Large Block Size Support Maximum Number of Concurrent I/Os Disk Mirroring Troubleshooting ******************** Introduction for Windows NT 4.0 ******************** Windows NT 4.0 is an operating system designed to run on processors using current technology. It provides a graphical user interface environment incorporating many high-level features (refer to the Microsoft Windows NT 4.0 documentation for details). An I/O manager handles I/O requests in Windows NT 4.0. To address a SCSI peripheral, the I/O manager goes through the appropriate drivers. Class drivers for hard disk, floptical, CD-ROM, printer, and scanner peripherals are provided in Windows NT 4.0. Other class drivers, provided by peripheral manufacturers, may be added to support new devices. Tape device support is built into the operating system itself and does not require a class driver. Microsoft provides the port driver and LSI Logic provides the miniport drivers, which are called SYMC8XX.SYS, SYM_HI.SYS, and SYM_U3.SYS. These drivers complete the path to an LSI Logic controller or processor with an optional SDMS SCSI BIOS. The next sections describe these drivers and their installation. * * * * * * * * * * * Features * * * * * * * * * * * * The SDMS device drivers support these features: o Ultra160 Data Transfers (for LSI53C1010, LSI53C1000) o Domain Validation (SYM_U3.SYS only) o Cyclic Redundancy Check (SYM_U3.SYS only) o Parallel Protocol Request (SYM_U3.SYS only) o Synchronous negotiation (including Fast SCSI/Ultra SCSI/Ultra2 SCSI) o Wide negotiation o Tagged command queuing o Multiple host adapters o Multiple Logical Unit Numbers (LUNs) o Disconnect/Reselect o Scatter/Gather o Provides Differential support o SCSI pass-through functionality o Disk array configurations with no LUN 0 o Disk array configurations with non-contiguous LUNs o Target initiated negotiation o Auto request sense o Maximum block size support: NT 4.0 - 1 Mbyte o NVRAM support (wide/sync parameters, SCSI Host ID) * * * * * * * * LSI Logic Devices Supported * * * * * * * * All LSI Logic devices and host adapters have undergone a name change. They have transitioned from a SYM prefix to an LSI prefix. No name changes have occurred for the SDMS Windows NT drivers. The SYMC8XX.SYS driver is named "Symbios PCI (53C8XX)" for driver installation. It supports the following devices and their associated LSI Logic host adapters: o LSI53C810, LSI53C810A, LSI53C810AE (LSI8100S, LSI8100ASP, LSI20810) o LSI53C815 (LSI815XS, LSI8150SP) o LSI53C825, LSI53C825A (LSI8250S, LSI8251S, LSI8251D, LSI8250ASP, LSI8251ASP, LSI8251AD) o LSI53C860, LSI53C860AE (LSI8600SP, LSI20860) o LSI53C875, LSI53C875E (LSI8750SP, LSI8751SP, LSI8751SPE, LSI8751D) o LSI53C876 (LSI22801, LSI22802) o LSI53C885 o LSI53C895, (LSI8951U, LSI8952U) The SYM_HI.SYS driver is named "Symbios PCI High Performance Driver" for driver installation. It supports the following devices and associated LSI Logic host adapters: o LSI53C895A (LSI8953U) o LSI53C896 (LSI22910, LSI21002, LSI22902) The SYM_U3.SYS driver is named "Symbios Ultra3 PCI SCSI Driver" for driver installation. It supports the following devices and associated LSI Logic host adapters: o LSI53C1010 (LSI8955U, LSI21040, LSI22903, LSI22915A, LSI21003) o LSI53C1000 (LSI20160, LSI20160L) * * * * * * * * * * * Description * * * * * * * * * * * SYMC8XX.SYS, SYM_HI.SYS, and SYM_U3.SYS meet the Microsoft specification for miniport drivers. These drivers allow connection of SCSI devices including disk drives, CD-ROMs, and tape drives for PCI-based machines. To support a new SCSI device, the Windows NT architecture requires that a class driver for that type device be present (usually supplied by Microsoft, or possibly by the peripheral manufacturer). No changes to SYMC8XX.SYS, SYM_HI.SYS, or SYM_U3.SYS are required. These drivers are only supported under Windows NT 4.0 and later versions. They do not run under earlier versions of Windows NT. SCSI commands are passed directly from a Windows application to the SCSI devices by using the SCSI pass-through facility (refer to the Microsoft Windows NT 4.0 documentation for details). This facility allows applications to directly control and access SCSI devices by filling in a data structure and calling into the port or class driver. The SYMC8XX.SYS and SYM_HI.SYS drivers support Ultra SCSI protocol, providing twice the raw data transfer rate of Fast SCSI for disk drives and LSI Logic host adapters that support Ultra SCSI. These drivers also support Ultra2 protocol, providing quadruple the raw data transfer rate of Fast SCSI. The SYM_U3.SYS driver supports Ultra160 SCSI protocol providing up to 160 Mbytes/s data transfer for double transition. Ultra160 includes double transition clocking, cyclic redundancy check, parallel protocol request, and domain validation. The standard Ultra3 SCSI protocol performs 80 megatransfers per second resulting in approximately double the synchronous data transfers rates of Ultra2 SCSI. CAUTION: Ultra SCSI requires more stringent SCSI bus cabling setups than Fast SCSI. Ultra2 and Ultra160 SCSI require Low Voltage Differential (LVD) termination. NOTE: The SDMS driver bundled in Windows NT 4.0 is named SYMC810.SYS. When Windows NT selects the bundled SDMS driver during setup, the driver information (that is, "Symbios C810 PCI SCSI Host Adapter") appears. Although this implies that the driver only supports the LSI53C810, it actually supports the LSI53C810, LSI53C810A, LSI53C815, LSI53C825, LSI53C825A, LSI53C860, LSI53C875, and LSI53C876. This driver does not "see" or support the LSI53C885, LSI53C895, LSI53C896, LSI53C895A, LSI53C1010, LSI53C1000 chipsets and any newer host adapters based on these chipsets that LSI Logic currently produces. Keep in mind that the Windows NT 4.0 setup only displays the driver information, and not every controller found by that driver. ********** Installing the SYMC8XX.SYS/SYM_HI.SYS/SYM_U3.SYS Driver *********** This section provides installation instructions for new and existing Windows NT systems. * * * * * * * * * * New System Installation * * * * * * * * * This procedure installs the SYMC8XX.SYS, SYM_HI.SYS, or SYM_U3.SYS driver onto a Windows NT 4.0 system. Use this procedure when installing Windows NT 4.0 onto an unused SCSI drive. Windows NT 4.0 automatically adds the driver to the registry and copies the driver to the appropriate directory. Choose one of two methods to install these drivers onto a Windows NT 4.0 system. 1. Boot directly from the Windows NT 4.0 CD-ROM -or- 2. Use Windows NT Boot Floppy Diskettes. Different steps are required depending on the method used. For Compaq/DEC systems based on the Alpha processor, CD-ROM installation is the only method available. The CD-ROM Installation and Boot Floppy Diskette Installation procedures are listed below. Select the appropriate installation for your system. * * * CD-ROM Installation * * * The driver that is bundled with Windows NT 4.0 is SYMC810.SYS. This driver supports controllers that are listed in the "NOTE" above. 1. Have the SDMS driver diskette available for inserting into the A: drive when prompted. Depending upon the media used to distribute the SDMS drivers (web or CDROM), you will create an SDMS driver diskette. Important: Read Steps 2 and 3 before performing the instructions contained within these steps. 2. Start the Windows NT 4.0 installation by booting from the Windows NT CD-ROM: For Intel-based systems, the system BIOS must support booting from a CD-ROM. SDMS SCSI BIOS settings may need to be changed to allow CD-ROM booting. For Alpha-based systems, select Supplimentary menu from the firmware Boot Menu, and then select Install Windows NT from CD-ROM. 3. Press the F6 key when the screen displays "Windows NT Setup." This must be done or else the new driver installed from the SDMS driver diskette will not be recognized. Note: Be sure to press the F6 key as any driver loaded later in the installation process is not recognized by the Windows setup. If F6 is not pressed, all devices controlled by the drivers are not available during Windows NT setup. 4. Choose S to specify an additional device when the screen displays "Setup could not determine the type of one or more mass storage devices...". NOTE: If this screen is not displayed as the first user input, then the F6 keypress was not seen by the setup program. Reboot the system and try again. The system prompts for the manufacturer-supplied hardware support disk. 5. Insert the appropriate SDMS Driver diskette containing the Windows NT driver required to support your LSI Logic adapter(s) and press Enter. 6. Depending on the driver being installed, either "Symbios PCI (53C8XX)", "Symbios PCI High Performance Driver", or "Symbios Ultra3 PCI SCSI Driver" is shown highlighted. Press Enter to proceed. NOTE: If more than one SDMS device driver needs to be installed, they can be installed one after the other using steps 4 through 6. Installation order is not important. NOTE: Current Windows NT 4.0 drivers can be downloaded from the LSI Logic web site at http://www.lsilogic.com. After you are connected to this web site, place your cursor on the Get Drivers option in the menu bar. Click on the Drivers selection. Choose the Windows NT operating system for SCSI and click on the Go button. Follow the instructions on subsequent screens to download the drivers. 7. Windows NT 4.0 should now recognize the Miniport driver(s) and the SCSI hardware. Press Enter to continue. 8. Follow the Microsoft Windows NT 4.0 installation procedure at this point. * * * Boot Floppy Disk Installation * * * The driver that is bundled with Windows NT 4.0 is SYMC810.SYS. This driver supports controllers that are listed in the "NOTE" above. 1. Have the SDMS driver diskette available for inserting into the A: drive when prompted. Depending upon the media used to distribute SDMS drivers (web or CDROM), you will create an SDMS driver diskette. Important: Read Step 2 before performing the instructions contained within this step. 2. Start the Windows NT 4.0 installation by booting from the Microsoft Setup floppy diskette. 3. Press Enter when the Welcome to Setup screen appears. The Windows NT 4.0 Workstation Setup window appears next. 4. Press S to skip automatic detection and do manual selection. A screen displays the message "Setup has recognized the following mass storage devices in your computer..." 5. Choose S to configure additional SCSI adapters when a screen displays the SCSI adapters found. 6. Move the highlight bar to Other and press Enter. The system prompts for the manufacturer-supplied hardware support disk. 7. Insert the appropriate SDMS driver diskette containing the Windows NT driver required to support your LSI Logic adapter(s) and press Enter. NOTE: Current Windows NT 4.0 drivers can be downloaded from the LSI Logic web site at http://www.lsilogic.com. After you are connected to this web site, place your cursor on the Get Drivers option in the menu bar. Click on the Drivers selection. Choose the Windows NT operating system for SCSI and click on the Go button. Follow the instructions on subsequent screens to download the drivers. 8. Depending on the driver being installed, either "Symbios PCI (53C8XX)", "Symbios PCI High Performance Driver" or "Symbios Ultra3 PCI SCSI Driver" is shown highlighted. Press Enter to proceed. NOTE: If more than one SDMS driver needs to be installed, they can be installed one after the other using steps 5 through 8. Installation order is not important. 9. The Windows NT Workstation Setup window reappears. If using an IDE CD-ROM for installation, press S to load additional drives. Another window appears. Scroll up and select: "IDE CD-ROM (ATAPI 1.2)/PCI IDE Controller" Press Enter. -or- If you have completed configuring additional SCSI adapters, press Enter. 10. Upon exiting, a screen displays the message "Setup will load support for the following mass storage devices(s). Press Enter to continue. This message implies that Windows NT recognizes the miniport driver and the SCSI hardware. At this point, simply follow the Microsoft Windows NT installation procedure. * * * * * * * * * Existing System Installation * * * * * * * * This procedure installs the SYMC8XX.SYS, SYM_HI.SYS, or SYM_U3.SYS driver onto an existing Windows NT system. NOTE: Windows NT 4.0 uses the Windows 95/98 user interface, resulting in minor changes to the procedure for updating SCSI drivers. * * * Windows NT 4.0 * * * 1. Boot Windows NT 4.0 and log on as Administrator. 2. Click on the Start button. Move to Settings-->Control Panel and click. 3. Double click on SCSI Adapters. 4. Click on the Drivers tab. If NCRSDMS.SYS, NCRC810.SYS, NCRC8XX.SYS, or SYMC810.SYS drivers are listed, and you are installing the SYMC8XX driver, select the driver(s) and choose Remove before adding the new SYMC8XX driver. Also, if the name of the driver you are installing (SYMC8XX.SYS, SYM_HI.SYS, or SYM_U3.SYS) is listed, remove it before adding the new driver. 5. Select OK when the Remove Driver message prompts: "Are you sure you want to remove this driver?". Another message may appear and prompt for a response: "The SCSI Adapter has been marked as a boot device ...". If so, click on the OK button. 6. Click Add. A list of installed adapters is displayed. 7. Click the Have Disk button. The system prompts for the manufacturer-supplied hardware support disk. 8. Insert the appropriate SDMS driver diskette containing the Windows NT 4.0 driver required to support your LSI Logic adapter(s). For the path to copy manufacturer's files from, enter: A:\WINNT\MINIPORT Select OK. 9. Depending on the driver being installed, either "Symbios PCI (53C8XX)", "Symbios PCI High Performance Driver", or "Symbios Ultra3 PCI SCSI Driver" is shown highlighted on the Install Driver menu. If it is not highlighted, select it. Choose OK. At this point, the following message may occur: "The driver(s) for this SCSI Adapter are already on the system. Do you want to use the currently installed driver(s) or install new one(s)?" Selecting Current uses the driver already on the system, and selecting New uses the driver on the diskette. Unless you want to use the older version already on the system, choose New. If you chose Current, go to step 11. 10. For the path to the OEM SCSI Adapter files, A:\WINNT\MINIPORT should be displayed. Select Continue. Then remove the floppy diskette from the A: drive. The System Settings Change message displays "You must restart your computer before the new settings take effect. Do you want to restart your computer now?" 11.Click on the Yes button to restart and reboot Windows NT 4.0. If you choose Cancel, remember that you must restart the computer to load the new driver. 12.If more than one SDMS driver needs to be installed, they can be installed one after the other without rebooting for each one. Installation order is not important. 13.Reboot your system to load the new miniport driver(s). * * * * * * * * * Performance Tuning for NT 4.0 * * * * * * * Windows NT 4.0 has registry entries that can be used to improve the performance of SCSI I/O for certain configurations. The tunable parameters are large transfer block size support and a guaranteed number of concurrent I/Os for a particular SCSI bus. * * * Large Block Size Support * * * The SYMC8XX.SYS, SYM_HI.SYS, and SYM_U3.SYS drivers can support up to a 1 Mbyte transfer size in Windows NT 4.0. However, in Windows NT 4.0, the default transfer size is 64 Kbytes. To enable a larger transfer size, an entry must be added to the registry, using the file sym_256K.reg. This file will set a 256 Kbytes maximum, but it can be edited to set other desired maximum transfer sizes. Important: Be sure to read the information in the sym_256K.reg data file before editing it. Choose one of two methods to add this registry setting: 1. Locate the sym_256K.reg data file (supplied with the driver files) using Windows Explorer and double click on the file. -or- 2. Type at the command prompt: regedit sym_256K.reg This inserts an entry in the registry to enable 256K block size support. Editing the sym_256K.reg can set any maximum block size between 64 Kbytes and 1 Mbyte (-8 Kbytes). The formula to calculate the proper value for MaximumSGList is: MaximumSGList = (Maximum Block Size)/4K +1 For 256K: 256K/4K = 64, add 1 for 65 (decimal) or 0x41(hexadecimal). The maximum value allowed for MaximumSGLIst is 255 or 0xFF. This denotes an absolute maximum transfer size of 1040384, which is 8K less than 1 Mbyte (1040384/4K = 0xFE, add 1 for 0xFF or 255). The system must be rebooted for the new registry setting to be effective. To reset the maximum block size to the default of 64K, follow the instructions above, except use symdfblk.reg as the data file. * * * Maximum Number of Concurrent I/Os (Guaranteed) * * * Windows NT 4.0 only guarantees a maximum of 32 concurrent I/Os active on a particular SCSI bus. However, due to the method of memory allocation, the actual limit of concurrent I/Os can vary greatly between various drivers or versions of drivers. This can have a huge impact on performance benchmarking between different driver versions or adapter vendors. In effect, one adapter may actually be able to have 70 or 80 I/Os outstanding, while another adapter could only have 32. This can also affect systems with high performance storage subsystems, such as disk arrays. In order to have a guaranteed number of concurrent I/Os, an entry must be added to the registry, using the file sym100io.reg. Important: Be sure to read the information in the sym100io.reg data file before editing it. Choose one of two methods to add this registry setting: 1. Locate the sym100io.reg data file (supplied with the driver files) using Windows Explorer and double click on the file. -or- 2. Type at the command prompt: regedit sym100io.reg This inserts an entry in the registry to guarantee a maximum of 100 concurrent I/Os per adapter. If a maximum other than 100 is desired, the sym100io.reg can be edited. The system administrator should be aware that increasing the number of concurrent I/Os from the default of 32 will use increasing amounts of non-paged pool memory. High values for this setting can degrade system performance. The system must be rebooted for the new registry setting to be effective. To reset the guaranteed number of concurrent I/Os to the default of 32, follow the instructions above, except use symdefio.reg as the data file. * * * Auto Request Sense * * * Enabling and Disabling Auto Request Sense is found in the Troubleshooting section. * * * * * * * * * * * Disk Mirroring * * * * * * * * * * Note: This section applies only to Intel x86-platforms where the SDMS 4.XX PCI SCSI BIOS is used. The SDMS 4.XX PCI SCSI BIOS loads only one image into the system memory at boot time regardless of how many host adapters are used in the system. All of the disk drives on all host adapters will be recognized through the INT13h function call. Because of this implementation, disk mirroring under Windows NT needs to be done by following instructions which might be different from the Microsoft documentation. To create an NT Fault Tolerant (FT) floppy diskette so that you can boot from the mirrored partition in case the primary partition fails, follow these steps: 1. Format a floppy diskette in drive A: using NT (File Manager or Windows Explorer) for use as a Fault Tolerant boot floppy. 2. From the root directory of the primary partition, copy NTLDR, NTDETECT.COM, and BOOT.INI to this floppy diskette. 3. Temporarily remove the read-only attribute of the BOOT.INI file so that it can be modified and saved. 4. Edit the BOOT.INI file on the FT floppy diskette and modify the following line where you want to boot the mirrored partition: multi(0)disk(0)rdisk(x)partition(y)\ where: multi(0) and disk(0) should always remain same. x = the drive number of the mirrored partition in the INT13 chain minus 80h. The drive number of the mirrored partition can be found during system bootup of the SDMS 4.XX PCI SCSI BIOS when the primary partition does not exist. It should say either BOOT (=80h), 81h, 82h, and higher. Therefore, the value of x would be 0 when BOOT, 1 when 81h, 2 when 82h, etc. y = the partition number on the drive (starts at 1 which equals single partition on the drive) The next example provides a scenario to better illustrate the above information. EXAMPLE: Two LSI Logic 8xx host adapters are in the system. The first HBA, HBA #0 which is the boot path, has two SCSI hard drives on ID 0 and ID 5. The second host adapter,HBA #1, has two SCSI hard drives on ID 2 and ID 4. Assuming that the SCSI bus scan starts from ID 0 and goes up, the drive number of INT13h will look like this: HBA #0, ID 0= BOOT (which is 80h) HBA #0, ID 5= 81h HBA #1, ID 2= 82h HBA #1, ID 4= 83h Now Windows NT 4.0 is installed on the boot drive, HBA #0 ID 0, and a mirrored partition is established on HBA #1 ID 2. If the primary partition fails, for example due to power failure, then the drive number of INT13h will change: HBA #0, ID 5= BOOT (which is 80h) HBA #1, ID 2= 81h HBA #1, ID 4= 82h Therefore, the following line should be used in the BOOT.INI file on the NT Fault Tolerant boot floppy to boot from the mirrored partition, HBA #1 ID 2. Note that rdisk(1) was calculated from x=81h minus 80h. multi(0)disk(0)rdisk(1)partition(1)\ 5. Save the BOOT.INI and restore the "read-only" attribute. * * * * * * * * * * Troubleshooting * * * * * * * * * * * Some potential problems and their suggested solutions are: * * * Problem * * * During installation, no SCSI devices are found. * * * Solution * * * a. Ensure that the custom setup is chosen on the Setup Method screen. b. Ensure that all devices are powered on and terminated correctly. c. Check that no devices have duplicate SCSI IDs. d. Make sure INT A is assigned for the PCI slot(s) where your SCSI host adapter(s) are installed. e. Ensure that all devices can be seen in the display banner of the SDMS SCSI BIOS at boot time. * * * Problem * * * System crashes during installation with a message indicating inaccessible boot device. * * * Solution * * * a. This error is usually associated with an IRQ, DMA channel, I/O (chip) address, or BIOS address conflict. Set the SCSI host adapter to use a different interrupt. b. A virus sometimes causes this error that infects the Master Boot Record of the boot device. Use a write-protected DOS bootable flex containing virus scanning and cleaning software to check for any viruses on the boot device, and remove if any are found. * * * Problem * * * A disk drive is recognized as seven different devices when only one is physically connected to the SCSI bus. * * * Solution * * * Older SCSI devices that incorrectly indicate to Windows NT 4.0 that they support multiple LUNs usually cause this error. Contact the device manufacturer for a firmware upgrade. * * * Problem * * * Problems with SCSI devices installation or operation. * * * Solution * * * If a SCSI device is not operating properly (either the device is not found or a SCSI interface error occurs during scanning), it is possible that the third-party device drivers do not support the auto request sense feature of LSI Logic host adapters. Disable the auto request sense feature as described below and try the device operation again. a. To disable the auto request feature, use the file symno_ar.reg (supplied with the SDMS NT driver files), and double click on the file in Windows Explorer or File Manager: -or- Type at the command prompt: regedit symno_ar.reg This inserts a registry entry that disables the auto request sense feature. The system must be rebooted for this change to take effect. b. To re-enable the auto request sense feature, use the file "sym_auto.reg" and perform one of the update methods described in the preceding paragraph. * * * Problem * * * Problems with certain SCSI devices when using an Ultra SCSI adapter. * * * Solution * * * Some SCSI devices do not function properly when the adapter attempts to negotiate Ultra SCSI transfer rates. If a device is not operating properly, check the transfer speed setting using the SDMS 4.XX PCI SCSI BIOS Configuration Utility (press Ctrl-C when the LSI Logic SDMS PCI BIOS banner appears during the system boot process). Devices that do not support Ultra SCSI should be set to a maximum of 10 Mbytes/s for 8-bits, and 20 Mbytes/s for 16-bits. * * * Problem * * * Problems with Ultra SCSI devices using Ultra SCSI protocol. * * * Solution * * * If the system is configured with an LSI Logic host adapter that supports Ultra SCSI and an Ultra SCSI device is on the SCSI bus, intermittent problems and possible system crashes can occur if the SCSI bus cable and terminators do not conform to the Ultra SCSI specification. a. Disable Ultra SCSI support for all devices by using the SDMS 4.XX PCI SCSI BIOS Configuration Utility (press Ctrl-C when the LSI Logic SDMS PCI BIOS banner appears during the system boot process). b. If the system operates properly without Ultra SCSI enabled, it is highly likely that the SCSI bus cable and terminators are not configured correctly for Ultra SCSI. Refer to the LSI Logic host adapter user's guide for information on Ultra SCSI cabling requirements. * * * Problem * * * The system hangs at boot, has a long boot time, or SCSI device not available. Some older SCSI devices do not tolerate Domain Validation operations. At system boot time, Domain Validation is performed to test the data integrity of the SCSI bus between the host adapter and each target device. With some older SCSI devices, these operations can cause the device to stop responding to SCSI commands. * * * Solution * * * Disable Domain Validation, either for a specific SCSI target or all adapters controlled by a specific driver. a. To disable Domain Validation for a specific SCSI target, use the SDMS 4.XX PCI SCSI BIOS Configuration Utility to set the sync rate to 0 (async) and the data width to 8. This target will be running in async/narrow mode and no Domain Validation operations will be performed on it. b. To disable Domain Validation for all host adapters controlled by this driver, use the file symno_dv.reg (supplied with the SDMS NT driver files). Either double click on the file in Windows Explorer or File Manager or type "regedit symno_dv.reg" at the command prompt. This inserts a registry entry that disables Domain Validation operations. The system must be rebooted for this change to take effect. c. To re-enable the Domain Validation feature, use the file "sym_domv.reg" and perform one of the update methods described in the preceding paragraph.