Computer Installation Guide - Dragon Clan Series

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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&TÆs (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 UserÆs 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