NCR SDMS NetWare Tuning Guide                          Page  1

Table Of Contents

1.  Introduction...........................................  2
  1.1.  Peripheral Device Dependent Optimizations .........  2
  1.2.  Flexibility........................................  2
  1.3.  Overall System Optimization........................  2
2.  Loading the NCR SDMS NetWare drivers...................  3
  2.1.  If using NetWare 3.1X..............................  3
  2.2.  If using NetWare 4.XX..............................  3
  2.3.  General Information................................  3
3.  Memory Allocation......................................  4
4.  Command Line Options Description.......................  5
  4.1.  Information Options................................  5
    4.1.1.  Verbose Mode...................................  5
    4.1.2.  Help Mode......................................  5
  4.2.  Device Oriented Options............................  6
    4.2.1.  Tag Command Queuing............................  6
    4.2.2.  Depth of Queue Tags............................  6
    4.2.3.  Base Timeout...................................  7
    4.2.4.  Sorting of Read requests.......................  7
  4.3.  Flexibility Options................................  8
    4.3.1.  Shared Interrupts..............................  8
    4.3.2.  Exclusion of Devices...........................  8
    4.3.3.  Wide SCSI......................................  9
    4.3.4.  Maximum Host  Adapters.........................  9
    4.3.5.  Maximum SCSI IDs............................... 10
    4.3.6.  Maximum LUNs................................... 10
  4.4.  System Optimizing Options.......................... 10
5.  Information Pertaining to a Specific Driver............ 11


NCR SDMS NetWare Tuning Guide                          Page  2

1.  Introduction

        A number of different command line options are provided with 
        the NCR SDMS device drivers for NetWare.  These parameters 
        allow users to fine tune their system for high performance and
        greater flexibility.  Considerations during the design of the 
        drivers included the behavior of the host systems, the 
        peripherals, the different software components co-existing 
        within the system, and the drivers themselves.

        Most system configurations will have certain features that 
        should be addressed by the SDMS drivers to achieve the best
        possible overall performance for the system.  Some examples 
        of the parameters which may be tuned in the driver are listed 
        below, along with the impact the tuning parameter may have on 
        a system given a particular functionality, or lack thereof.  
        In parentheses following the example are the driver options 
        associated with the example.

  1.1.  Peripheral Device Dependent Optimizations:

        Some devices support tagged queue commands very efficiently, 
        e.g. AT&T’s (formerly NCR) disk array subsystems, while others
        show a significant degradation in performance when a number of 
        queued requests exceeds a certain value. (qtags, qdepth)

        Most disk drives have an onboard read cache that is used by the
        drive controller to read ahead data. The driver may take 
        advantage of this cache  by maximizing the cache hits and 
        ensuring a higher data transfer rate.  However, there are 
        devices that do not have an onboard cache, and implementation 
        of the performance algorithm results in a greater processing 
        overhead with no advantage, and as such an overall performance
        degradation. (sort)

        Devices differ in their response times to requests.  To ensure 
        that the driver can handle devices with various response times,
        an option to tune the timeout value is available.(timeout)
        
  1.2.  Flexibility
   
        In order to allow flexibility of control of devices on the 
        system, an option is provided to determine which of the devices
        the driver needs to exclude from taking control over.  This 
        allows independent software vendors to provide value added 
        applications to directly control certain devices (e.g. Backup 
        applications) via the ASPI or the CAM interface.  (xcl) 

        For embedded systems, or other systems with fixed configura-
        tions, a user can limit the amount of dynamically allocated 
        memory by choosing to set maximum limits on the number of host 
        adapters, devices and logical units to support.
        (max_hbas, max_id, max_lun)

  1.3.  Overall System Optimization

        A driver designed for a networked file server environment also
        has to optimize the performance in tandem with the other 
        components of the system. In order to avoid monopoly on the I/O
        bus, users can configure the size of the blocks for transfer 
        across the SCSI bus, ensuring that other components get fair 
        access to the I/O bus.  (max_kb)

NCR SDMS NetWare Tuning Guide                          Page  3

2.  Loading the NCR SDMS NetWare drivers

  2.1.  NetWare 3.1X

        The following files should be copied to the directory in 
        which the server.exe file resides:

           NCRSDMS3.DSK - For general support of SCSI disk and CD-ROM 
                          devices attached to NCR based PCI-SCSI 
                          controllers, such as embedded controllers on
                          the motherboard  utilizing the NCR 53C800 
                          family of integrated circuits. (NCR 53C810, 
                          53C815, 53C820, 53C825 chips) and the NCR 
                          family of PCI Host Bus Adapters (8100S, 
                          8150S, 8250S, 8251S, 8251D, etc.).

           ASPICAM3.NLM - For ASPI programming interface  support, 
                             including tape support.

        At the NetWare 3.1X prompt, type in 
           load NCRSDMS3 <options>
           load ASPICAM3  (Only necessary if ASPI support is desired)

  2.2.  NetWare 4.XX

        The following files should be copied to the directory in which
        the server.exe file resides:
           NCRSDMS4.DSK - For general support of SCSI disk and CD-ROM 
                             devices attached to NCR base PCI-SCSI 
                          controllers, such as embedded controllers on
                          the motherboard utilizing the NCR 53C800 
                          family of integrated circuits. (NCR 53C810, 
                          53C815, 53C820, 53C825 chips), and the NCR 
                          family of PCI Host Bus Adapters (8100S, 
                          8150S, 8250S, 8251S, 8251D, etc.).
           NCRSDMS4.DDI - For NetWare 4.XX Installation Support.
           ASPICAM4.NLM - For ASPI programming interface support, 
                             including tape support.

        At the NetWare 4.XX prompt, type in 
           load NCRSDMS4 <options>
           load ASPICAM4  (Only necessary if ASPI support is desired)

  2.3.  General Information 

        These drivers may be loaded only once.  If any changes are 
        necessary to the driver options, then the drivers must be 
        unloaded and then reloaded with the appropriate options.  
        If these changes are to be permanent, and the drivers are 
        loaded automatically at server boot time, then these options 
        must also be specified in the startup.ncf file. 

        For more information on installing and using the NCR SDMS 
        NetWare drivers, please refer to the NetWare section in the 
        SCSI Device Management System NCR SDMS 3.0 User’s Guide.

NCR SDMS NetWare Tuning Guide                          Page  4

3.  Memory Allocation

        The driver allocates memory for certain structures based upon 
        the maximum number of SCSI IDs (max_id), LUNs (max_lun) and 
        paths (max_hbas) that may be used in the system.  The amount 
        of memory allocated is based on the following formula: 

        437 bytes of memory are allocated for the structure, so
           Memory allocated = 437 * max_hbas * max_lun * max_id.

        So for default allocations, the amount of memory allocated is:
           Memory allocated = 437 * 8 * 4 * 32 =  447,448 bytes 
                                               =  437 KB

        If, for example, 
           only one host adapter is installed (or using an NCR based 
               PCI-SCSI embedded controller and no add in HBAs),
           only one LUN per device will be used, and 
           the bus is narrow (e.g. max. 8 SCSI IDs), 
        then by setting the appropriate options, the amount of memory 
        allocated will be:
           Memory allocated = 437 * 1 * 1 * 8 = 3496 bytes,
                                           approximately 3.4 KB

NCR SDMS NetWare Tuning Guide                          Page  5

4.  Command Line Options Description

        The NCRSDMS3.DSK and NCRSDMS4.DSK drivers have many tuning 
        parameters.
        (At this time there are no command line options for the 
        ASPICAM3.NLM or ASPICAM4. NLM drivers.) 

        Following is a list of tuning parameters available, including 
        the default option and a list of valid options.  Following 
        each parameter is a description of when a parameter should be 
        used and any impact its use/disuse might incur.

        If an option is specified but the assignment is not valid, 
        then the default value will be used. The NCRSDMS3.DSK and 
        NCRSDMS4.DSK drivers will be referred to in the remainder of 
        this document as NCRSDMSX.DSK, where X refers to the 
        appropriate NetWare operating system version.

        The options described below are used by placing the specified 
        characters on the load command line for the NCRSDMS driver. 
        For example, if the Verbose Mode command line option is 
        desired in NetWare 3.1X, the load command line should look 
        like this:
           load NCRSDMS3 -v  

  4.1.  Information Options

    4.1.1.  Verbose Mode: 

        Command line option:  -v
        Function:  Display the current settings of all driver options.

        This option will indicate the option settings for this load 
        of the driver.

    4.1.2.  Help Mode: 

        Command line option:  -? or -h
        Function:  Display the options available in the driver.
        Possible Impact:  The driver will not load with -? or -h 
                          specified.

        This option may be specified on the command line for a brief 
        description of each of the options available in the driver, 
        as well as valid values for each option.  If the -? and other 
        options are specified, the help screen will be invoked, the 
        other options will be ignored and the driver will not be 
        loaded.


NCR SDMS NetWare Tuning Guide                          Page  6

  4.2.  Device Oriented Options:

    4.2.1.  Tag Command Queuing: 

        Command line option:  qtags=<option>
        Default value:  enable
        Valid options:  enable, disable
        Function:  Enable/disable tag command queuing for the devices 
        Possible Impact:  Tagged commands may result in improved I/O
                          throughput in devices that support such an
                          option.

        Enabling the option results in the driver issuing tagged 
        command requests to the devices that support tagged queuing.  
        Devices that do not support tagged queuing are not issued 
        tagged requests.  Depending on the drive controller, throughput
        of the device may be increased by the use of queue tags, 
        although an optimal number of queue tags is based on the 
        specific device type.

    4.2.2.  Depth of Queue Tags: 

        Command line option:  qdepth=<option>
        Default value:  10
        Valid options:  0-128
        Function:  Set the depth of the queue for tag command queuing.
                   This value designates the depth of the queue per 
                   LUN (I_T_L nexus), e.g. this value designates the 
                   depth of the queue per device, or per LUN, if a 
                   device has multiple LUNs.
        Possible Impact:  Must be set to optimize the performance of 
                          tagged command queuing.

        This option is valid only when tag command queuing (qtags) is 
        enabled, which it is by default. 0 is equivalent to 
        qtags=disable, and takes precedence over the setting of the 
        qtags option.  While the actual depth of the queue depends on 
        the specific drive controller, for single drives values of 
        about 10-30 are typically most optimal.  A greater number may 
        be optimal for peripherals such as disk arrays.  Users should 
        experiment with various qdepth values to determine the most 
        optimal performance of their particular setup.  The optimal 
        qdepth value is based on different aspects of the system, 
        including but not limited to: the processor, the available 
        memory, the disk drives, and other peripherals.
        Note:  The driver supports a maximum of 128 qtags per 
               controller at any given time.  The driver may allocate 
               fewer qtags per device if this limit is being reached. 
                  

NCR SDMS NetWare Tuning Guide                          Page  7

    4.2.3.  Base Timeout: 

        Command line option:  timeout=<option>
        Default value:  30 
        Valid options:  Any integer value 30 to 999999999 
        Function:  Specify the minimum value (in seconds) for command 
                   timeout.
        Possible Impact:  Insure system integrity when using a slow 
                          device.  Performance may be reduced.

        The amount of time, in seconds, allowed for a command is 
        dynamically determined by the number of pending commands and 
        a base offset, or base timeout.  If a device is slow, this 
        value may be increased to insure the device has adequate time 
        to respond to a command issued to it before the command times 
        out.  This timeout is determined based on the number of 
        outstanding IOs per device.

    4.2.4.  Sorting of Read requests: 

        Command line option:  sort=<option>
        Default value:  enable
        Valid options:  enable, disable
        Function:  Enable/disable sorting of read commands to be 
                   issued to devices.
        Possible Impact:  Enabling will normally yield increased 
                          performance based on the target device 
                          controller.

        If the devices connected to the host adapter(s) are of a 
        non-buffered architecture, such as AT&T's (formerly NCR) 
        6298 disk array, then sorting of reads may result in a 
        performance degradation, since the absence of cache 
        provides no benefit for sorted requests. In this instance 
        the sort option should be disabled.  On most disk drives, an 
        on-board cache allows for reading ahead of data, and by 
        sorting read requests,  the probabilities of achieving a 
        cache hit are greatly increased, thus increasing the overall 
        performance of the driver.


NCR SDMS NetWare Tuning Guide                          Page  8

  4.3.  Flexibility Options

    4.3.1.  Shared Interrupts: 

        Command line option:  shared_int=<option>
        Default value:  disable
        Valid options:  enable, disable
        Function:  Support shared interrupts.
        Possible Impact:  Enabling may cause a performance degradation.

        The shared interrupt option should be enabled any time a PCI 
        card other than NCR Host Adapters are added to a system which
        assigns all PCI cards the same interrupt value.  The added 
        card must be able to support shared interrupts. The driver 
        automatically handles the case of more than one NCR host 
        adapter sharing an interrupt.

    4.3.2.  Exclusion of Devices: 

        Command line option:  xcl=<device>[:device ...]
        Default value:  All devices recognized by the driver, i.e. 
                        no devices are excluded.
        Valid options:  p,i,l  
                       (Multiple devices may be specified with a colon
                       separator) where p is the Path designator, and 
                       is in the range 0-7, i is the SCSI ID 
                       designator, and is in the range 0-31, and l 
                       is the LUN designator, and in the range 0-7.  
                       The LUN parameter is optional.
                       Multiple devices may be excluded so long as the
                       string does not exceed 35 characters in length 
                       and devices are separated by colons.  
        Examples:  xcl=1,2,3 to exclude LUN 3 of the device at SCSI 
                                ID 2 on Path 1.
                   xcl=1,2,3:2,5 to exclude LUN 3 of the device at 
                                    SCSI ID 2 on Path 1, and all LUNs on 
                                 the device at SCSI ID 5 on Path 2 
        Function:  Allows for specifying certain devices not be 
                   recognized by the driver.
        Possible Impact:  Device(s) may not be directly accessed via 
                          NCRSDMSX driver.

        This option is available so that specific devices may be 
        excluded from being recognized and directly accessed by the 
        NCRSDMSX.DSK drivers.  These devices are not registered with 
        the operating system for use by the driver. Other 
        applications/drivers can then take over the control of such 
        devices. This option is available for support of third party 
        vendors who write their own SCSI control applications.


NCR SDMS NetWare Tuning Guide                          Page  9

    4.3.3.  Wide SCSI: 

        Command line option:  wide=<option>
        Default value:  enable
        Valid options:  enable, disable
        Function:  Enable/Disable support of Wide SCSI.
        Possible Impact:  No Wide SCSI Support available.

        This option specifically allows the user to disable support of
        wide SCSI when using  a wide SCSI controller.  This option 
        should be set to "disable" if a wide SCSI device is present on
        the system, but a narrow SCSI cable is connected somewhere on 
        the bus between the wide SCSI host adapter  and the wide 
        device, thus prohibiting the transfer of wide data.  If this 
        option is set to "disable", the wide device may still be used,
        but all data transferred to/from the device will be narrow 
        (8 bit).  The driver will not initiate a wide SCSI transfer 
        request negotiation.

    The following three options affect the amount of memory used by 
    the driver.  Please see the section above on memory allocation for 
    information on how memory is allocated by the driver, and to get 
    an approximate feel for the amount of memory which may be saved by
    invoking these parameters.

    4.3.4.  Maximum Host  Adapters: 

        Command line option:  max_hbas=<option>
        Default value:  8
        Valid options:  1-8
        Function:  Specify the maximum number of Host Bus Adapters to 
                   support.
        Possible Impact:  If number is reduced, may allow for 
                          reduction in memory used by the driver.

        This parameter may be used to optimize the use of dynamically 
        allocated memory by the driver. If less than 8 NCR based PCI 
        host adapters, including any on board (built in to) the 
        motherboard, are being used, this parameter will allow for a 
        reduction in the total memory being used for the driver.


NCR SDMS NetWare Tuning Guide                          Page  10

    4.3.5.  Maximum SCSI IDs: 

        Command line option:  max_id=<option>
        Default value:  32
        Valid options:  8-32
        Function:  Specify the maximum number of SCSI IDs each host 
                   adapter board should support.
        Possible Impact:  If number is reduced, may allow for 
                          reduction in memory used by the driver.

        This parameter may be used to optimize the use of dynamically 
        allocated memory by the driver.  If all the host adapters, 
        including any SCSI controllers on the motherboard are 
        connected to less than 31 devices, a user can reduce the size 
        of the dynamically allocated memory by setting this value to 
        the maximum number of devices on any of the SCSI controllers. 

    4.3.6.  Maximum LUNs: 

        Command line option:  max_lun=<option>
        Default value:  4
        Valid options:  1-8
        Function:  Specify the maximum number of LUNs each host 
                   adapter board should support per SCSI id.
        Possible Impact:  If number is reduced, may allow for 
                          reduction in memory used by the driver.

        This parameter may be used to optimize the use of dynamically 
        allocated memory by the driver.  If less than 8 LUNs are being
        used per  NCR based PCI host adapter SCSI id, this parameter
        will allow for a reduction in the total memory being used for 
        the driver. 

  4.4.  System Optimizing Options

    4.4.1.  Maximum Block Size for Concatenation: 
        Command line option:  max_kb=<option>
        Default value:  32767
        Valid options:  0-32767
        Function:  Set the maximum number of KB that may be written 
                   to disk at one time.
        Possible Impact:  A high number may result in more data being 
                          transferred in a single data phase.

        Specify the maximum size block in Kilobytes which may be 
        written to disk in one data transfer phase. This ensures 
        that when requests are being concatenated, the maximum size 
        of the concatenated request would not exceed the specified 
        value. If individual requests themselves are greater than this
        specified value, no action would be taken.


NCR SDMS NetWare Tuning Guide                          Page  11

5.  Information Pertaining to a Specific Driver

    This document addresses options available on the NCR SDMS 
    NetWare drivers, version 3.05.00.  For information pertaining 
    to a specific driver, please do one of the following:

        For NetWare version 4.XX, consult the NCRSDMS4.DDI file for 
        options available for NCRSDMS4.DSK.  This may be accessed via 
        the NetWare install utility.

        For versions of the driver 3.05.00 and later, use the -? 
        option on the command line of the NCRSDMSX.DSK driver