Document revision date: 15 July 2002

Many system parameters can affect other parameters and the performance of the system. For this reason, Compaq recommends that you use the command procedure SYS$UPDATE:AUTOGEN.COM (AUTOGEN) to manage system parameters. For information about AUTOGEN, see Section 15.4.

The System Management utility (SYSMAN) and the System Generation utility (SYSGEN) also allow you to manage system parameters. Although these utilities are not generally recommended for changing parameter values, you can use one of these utilities for the following reasons:

• To display system parameters and their values on a VAX or Alpha system
• To display system parameters and their values for systems in an OpenVMS Cluster environment
• To temporarily modify a single parameter that has little effect on other parameters

Compaq recommends that you use the AUTOGEN command procedure to tune your system. If you use the System Management utility (SYSMAN) or the System Generation utility (SYSGEN) to modify system parameter values, and you do not include these changes in the AUTOGEN parameter file MODPARAMS.DAT, these changes will be overridden the next time you run AUTOGEN.

If you used SYSMAN or SYSGEN to change parameter values in the past, use the following procedure to convert your parameter settings to work with AUTOGEN. This procedure explains how to add your customized parameter settings to MODPARAMS.DAT so they will be retained when you run AUTOGEN.

Before performing this task, you should understand AUTOGEN, feedback, and the AUTOGEN parameter file MODPARAMS.DAT, as explained in Section 15.4.

1. Save the parameter values that the system is now using as follows:

   $ RUN SYS$SYSTEM:SYSMAN SYSMAN> PARAMETERS USE ACTIVE SYSMAN> PARAMETERS WRITE SYS$SYSTEM:nodename_PARAMS_CURRENT.PAR

2. Write a listing of the active parameter values to an ASCII file named nodename_PARAMS.OLD as follows:

   SYSMAN> PARAMETERS SHOW/ALL/OUTPUT=nodename_PARAMS.OLD SYSMAN> PARAMETERS SHOW/SPECIAL/OUTPUT=nodename_PARAMS_SPECIAL.OLD SYSMAN> EXIT $ APPEND nodename_PARAMS_SPECIAL.OLD nodename_PARAMS.OLD

   
   You will use this file in step 6.

3. Edit AUTOGEN's parameter file SYS$SYSTEM:MODPARAMS.DAT to define symbols to specify values for the following parameters:
   • Parameter values that are not calculated by AUTOGEN, such as SCSNODE and SCSSYSTEMID. Refer to the AUTOGEN description in the OpenVMS System Management Utilities Reference Manual for a table of the parameters calculated by AUTOGEN.
   • Any parameter values that must be adjusted to suit your system work load, for example, GBLPAGES and GBLSECTIONS.
   
   To specify a value, define symbols using the format MIN_parameter, MAX_parameter, or ADD_parameter rather than specifying an explicit value. For example:

   $ EDIT SYS$SYSTEM:MODPARAMS.DAT

   SCSNODE = "MYNODE" ! Not calculated by AUTOGEN SCSSYSTEMID = 10001 ! Not calculated by AUTOGEN MIN_GBLPAGES = 10000 ! Needed for MCS, BLISS32, and ADA MIN_GBLSECTIONS = 600 ! Needed for MCS, BLISS32, and ADA

   
   To help you track the changes you make in MODPARAMS.DAT, add comments to each line, preceded by an exclamation point (!). For information about defining symbols in MODPARAMS.DAT, see Section 15.5.1.

4. Run AUTOGEN, but do not reboot. Use one of the following commands, depending on your system:
   • If the system has run a typical work load for more than 24 hours since last booting:

     $ @SYS$UPDATE:AUTOGEN SAVPARAMS SETPARAMS FEEDBACK

     
     The SAVPARAMS phase collects feedback information about resource use on the running system; this information is used by AUTOGEN. This command creates a feedback report named SYS$SYSTEM:AGEN$PARAMS.REPORT, which tells you about peak resource use.

   • If you want to use a previously collected feedback file:

     $ @SYS$UPDATE:AUTOGEN GETDATA SETPARAMS FEEDBACK

     
     If you start from the GETDATA phase, AUTOGEN does not collect current feedback.

   • If this is a new system (that is, it has no feedback) or the system has had little activity since last boot (for example, over the weekend) so there is no valid feedback file:

     $@SYS$UPDATE:AUTOGEN GETDATA SETPARAMS CHECK_FEEDBACK

     
     Use the CHECK_FEEDBACK parameter to let AUTOGEN determine whether the feedback is valid.

5. Write a listing of the new parameter values to an ASCII file as follows:

   $ RUN SYS$SYSTEM:SYSMAN SYSMAN> PARAMETERS USE CURRENT SYSMAN> PARAMETERS SHOW /ALL /OUTPUT=nodename_PARAMS.NEW SYSMAN> PARAMETERS SHOW /SPECIAL /OUTPUT=nodename_PARAMS_SPECIAL.NEW SYSMAN> EXIT $ APPEND nodename_PARAMS_SPECIAL.NEW nodename_PARAMS.NEW

6. Compare the old and new parameter values as follows:

   $ DIFFERENCES/PARALLEL/OUTPUT=nodename_PARAMS.DIF/MATCH=5 - _$ nodename_PARAMS.OLD nodename_PARAMS.NEW

7. Print the differences file you created in step 6 (named in the format nodename_PARAMS.DIF). Print the file on a 132-column line printer to make the output easier to read.
8. Compare the numbers in the two columns following each parameter name column. The left column shows the old value; the right column shows the new value. Figure 15-1 illustrates sample output.

   Figure 15-1 Old and New Parameter Values

   ---

   
9. Make any adjustments in MODPARAMS.DAT using symbols prefixed by MIN_, MAX_, or ADD_. For example, if AUTOGEN calculated a smaller value for GBLPAGES, you might specify a minimum value for this parameter as follows:

   MIN_GBLPAGES = 10000

   
   If you originally specified a parameter value in MODPARAMS.DAT (in step 3) but the parameter has not been changed, verify the following data:

   • The parameter name is spelled correctly and completely (not abbreviated). In MODPARAMS.DAT, AUTOGEN sees parameter names as symbol assignments. AUTOGEN cannot equate a symbol to the corresponding system parameter unless it is spelled correctly. Look in AGEN$FEEDBACK.REPORT for any error messages AUTOGEN might have written.
   • The value is correct: count the digits and make sure no commas are present.
   • The parameter occurs only once in MODPARAMS.DAT.
   • The parameter is not commented out.
   
   For most parameters, if the new value is greater than the old value, you can accept AUTOGEN's setting. If the new value is less than the old value, Compaq recommends that you retain the old value because the system may not have been using that resource when running AUTOGEN.
   For example, you might have used SYSMAN to increase GBLPAGES to 10,000 to accommodate layered products, but have not specified that change in MODPARAMS.DAT. AUTOGEN might calculate that the system needs only 5000 global pages. When you reboot after running AUTOGEN, not all of your layered products may be installed, and you might receive the system message GPTFULL, "global page table full," indicating that the system needs more GBLPAGES.
10. Repeat from step 3 until you are satisfied with the new parameter values.
    If necessary, make further changes in MODPARAMS.DAT, run AUTOGEN again, and verify the changes as before. Usually after this second pass of AUTOGEN, the parameter values will be stable and you can then reboot.
11. Reboot. When you reboot, the system will use the new parameter values. Using AUTOGEN to reboot or rebooting right away is not necessary. However you must reboot before the system uses the new parameter values.
    If the system does not boot, perform a conversational boot and use the backup parameter file you created in step 1:

    SYSBOOT> USE SYS$SYSTEM:nodename_PARAMS_CURRENT.PAR SYSBOOT> CONTINUE

    When you enter the CONTINUE command, the system boots with the parameter values you saved before running AUTOGEN.
    After the system has booted, if you want to use the old parameter values you can enter the following commands:

    $ RUN SYS$SYSTEM:SYSMAN SYSMAN> PARAMETERS USE SYS$SYSTEM:nodename_PARAMS_CURRENT.PAR SYSMAN> PARAMETERS WRITE CURRENT SYSMAN> EXIT

12. Run AUTOGEN using feedback regularly to ensure that the resources of your system match your system work load. For information about running AUTOGEN using feedback, see Section 15.5.

The AUTOGEN command procedure, SYS$UPDATE:AUTOGEN.COM, is provided on your distribution kit, and runs automatically when your system is installed or upgraded to set appropriate values for system parameters. In addition, Compaq recommends that you run AUTOGEN when you want to reset values for system parameters or to resize page, swap, and dump files. The new values and file sizes take effect the next time the system boots.

AUTOGEN only calculates certain significant system parameters. Refer to the AUTOGEN section of the OpenVMS System Management Utilities Reference Manual for a table of system parameters affected by AUTOGEN calculation.

When to Run AUTOGEN

Compaq recommends running AUTOGEN in the following circumstances:

• During a new installation or upgrade. (This happens automatically as part of the installation or upgrade procedure.)
• Whenever your work load changes significantly.
• When you add an optional (layered) software product. See the specific product documentation for installation requirements. Certain layered products might require you to execute AUTOGEN to adjust parameter values and page and swap file sizes. (For information about using AUTOGEN to modify page and swap files, see Section 16.16.1.)
• When you install images with the /SHARED attribute; the GBLSECTIONS and GBLPAGES parameters might need to be increased to accommodate the additional global pages and global sections consumed.
• On a regular basis to monitor changes in your system's work load. You can automate AUTOGEN to regularly check feedback and recommend system parameter changes. Section 15.6 describes a batch-oriented command procedure that runs AUTOGEN in feedback mode on a regular basis and automatically sends the feedback report to an appropriate Mail account.
• Periodically to provide adequate swapping file space. Use the FEEDBACK option and make sure the system has been up long enough (at least 24 hours) and that the load is typical. Also, make sure the SYS$SYSTEM:MODPARAMS.DAT file does not contain a hardcoded SWAPFILE value, which prevents AUTOGEN from correctly sizing the swapping files.

AUTOGEN Operations

AUTOGEN executes in phases. Depending on which phases you direct it to execute, AUTOGEN performs some or all of the following operations:

• Collects the following types of data:
  • Feedback (from the running system)
  • The hardware configuration (from the system)
  • Parameter requirements supplied by you (from MODPARAMS.DAT)
  • Parameter requirements supplied by Compaq
• Calculates appropriate new values for significant system parameters (listed in the AUTOGEN section of the OpenVMS System Management Utilities Reference Manual)
• Creates a new installed image list
• Calculates the sizes of system page, swap, and dump files
• Adjusts the sizes of system page, swap, and dump files values of system parameter values, if necessary
• Optionally shuts down and reboots the system

Invoking AUTOGEN

To invoke AUTOGEN, enter a command in the following format at the DCL prompt:

@SYS$UPDATE:AUTOGEN [start-phase] [end-phase] [execution-mode]

where:

start-phase	Is the phase where AUTOGEN is to begin executing. Section 15.4.3 lists the AUTOGEN phases.
end-phase	Is the phase where AUTOGEN is to complete executing. Section 15.4.3 lists the AUTOGEN phases.
execution-mode	Is one of the following modes: FEEDBACK---Use feedback. NOFEEDBACK---Do not use feedback. CHECK_FEEDBACK---Use feedback if it is valid. If feedback is invalid, ignore it, but continue executing through the end phase. Blank (no execution mode specified)---Use feedback if it is valid. If it is not valid, quit before making any modifications.

For detailed information about invoking AUTOGEN, and the command line parameters you can specify, refer to the AUTOGEN section of the OpenVMS System Management Utilities Reference Manual.

Controlling AUTOGEN Operations

Table 15-1 summarizes the methods for controlling AUTOGEN behavior.

Table 15-1 Controlling AUTOGEN

To Control...	Use This Method...
Which operations AUTOGEN is to perform	Specify a start phase and an end phase when you invoke AUTOGEN.
Parameter values set by AUTOGEN	Specify values in the AUTOGEN parameter file MODPARAMS.DAT. Periodically examine the results of calculations that AUTOGEN makes to determine whether AUTOGEN has drawn the correct conclusions about your hardware configuration and to be sure the system parameter values are appropriate for your workload requirements. If the values are not appropriate, adjust them by specifying desired values in MODPARAMS.DAT. For more information on MODPARAMS.DAT, see Section 15.4.4.
AUTOGEN's use of feedback information	Specify an execution mode when you invoke AUTOGEN. AUTOGEN can often improve system performance by using dynamic feedback gathered from the running system. However, feedback information is not always valid or appropriate. For more information, see Section 15.4.1.

15.4.1 AUTOGEN Feedback

AUTOGEN feedback minimizes the need for you to modify parameter values or system file sizes. Instead, feedback allows AUTOGEN to automatically size the operating system based on your actual work load. Sizing is the process of matching the allocation of system resources (memory and disk space) with the workload requirements of your site.

Feedback is information, continuously collected by the operating system executive, about the amount of various resources the system uses to process its work load. The information is collected when exception events occur, so the collection does not affect system performance. When run in feedback mode, AUTOGEN analyzes this information and adjusts any related parameter values.

AUTOGEN feedback affects the following resources (for a complete list of the affected system parameters, refer to the AUTOGEN section of the OpenVMS System Management Utilities Reference Manual):

• Nonpaged pool
• Paged pool
• Lock resources
• Number of processes
• Global pages
• Global sections
• File system caches
• System logical name table sizes
• Page files
• Swap files

Feedback is gathered during AUTOGEN's SAVPARAMS phase and is written to the file SYS$SYSTEM:AGEN$FEEDBACK.DAT. This file is then read during the GETDATA phase. (See Section 15.4.3 for more information about AUTOGEN phases.)

Feedback is useful only if it accurately reflects the system's normal work load. For this reason, AUTOGEN performs some basic checks on the feedback and issues a warning message for either of the following conditions:

• The system has been up for less than 24 hours.
• The feedback is over 30 days old.

Whenever you modify the system (for example, a hardware upgrade, a change in the number of users, an optional product installation), you should operate in the new system environment for a period of time, and then execute AUTOGEN again starting from the SAVPARAMS phase.

On VAX systems, you can define the logical name AGEN$FEEDBACK_REQ_TIME to specify, in hours, a minimum age required for feedback. For more information, see Section 15.5.2.

When AUTOGEN runs, it displays whether feedback is used, as follows:

Feedback information was collected on 21-JAN-2000 14:00:08.53 Old values below are the parameter values at the time of collection. The feedback data is based on 21 hours of up time. Feedback information will be used in the subsequent calculations

15.4.2 Feedback Report (AGEN$PARAMS.REPORT)

Decides whether to use the system parameter values and system file sizes calculated by AUTOGEN. To help in your decision making, AUTOGEN generates a report file (SYS$SYSTEM:AGEN$PARAMS.REPORT) that includes the following information:

• All parameters and system files directly affected by the feedback
• Current values
• New values
• The feedback used in each parameter calculation
• Any user- or Compaq-supplied modifications found in MODPARAMS.DAT
• Any advisory or warning messages displayed during AUTOGEN's operations
• On VAX systems, any user- or Compaq-supplied modifications found in VMSPARAMS.DAT
• On Alpha systems, the parameters found during the GENPARAMS phase

Suppressing Informational Messages

To suppress the display of informational messages, define the AGEN$REPORT_NO_INFORMATIONALS logical to TRUE. Messages are entered in SYS$SYSTEM:AGEN$PARAMS.REPORT regardless of the value of AGEN$REPORT_NO_INFORMATIONALS.

Filtering DCL Statements from Your Report

The feedback report will contain DCL statements in MODPARAMS.DAT that are not simple assignments to system parameters or the ADD_, MAX_, or MIN_ extensions. To filter these statements out of the report, begin each statement in MODPARAMS.DAT with a dollar sign ($).

Example 15-1 Sample AUTOGEN Feedback Report

AUTOGEN Parameter Calculation Report on node: NODE22 This information was generated at 23-APR-2000 01:45:47.87 AUTOGEN was run from GETDATA to TESTFILES using FEEDBACK ** No changes will be done by AUTOGEN ** The values given in this report are what AUTOGEN would have set the parameters to. Processing Parameter Data files ------------------------------- ** WARNING ** - The system was up for less than 24 hours when the feedback information was recorded. This could result in feedback information that does not accurately reflect your typical work load. Including parameters from: SYS$SYSTEM:MODPARAMS.DAT The following was detected within MODPARAMS.DAT Please review immediately. ** INFORMATIONAL ** - Multiple MIN values found for MIN_CHANNELCNT. Using MODPARAMS value (550) which is superseding OpenVMS value (255) ** INFORMATIONAL ** - Multiple MIN values found for MIN_SWPOUTPGCNT. Using MODPARAMS value (1000) which is superseding OpenVMS value (500) ** INFORMATIONAL ** - Multiple MIN values found for MIN_PQL_DWSEXTENT. Using MODPARAMS value (11000) which is superseding OpenVMS value (1024) ** INFORMATIONAL ** - Multiple MIN values found for MIN_PQL_MWSEXTENT. Using MODPARAMS value (11000) which is superseding OpenVMS value (1024) Feedback information was collected on 22-APR-2000 14:00:07.70 Old values below are the parameter values at the time of collection. The feedback data is based on 13 hours of up time. Feedback information will be used in the subsequent calculations Parameter information follows: ------------------------------ MAXPROCESSCNT parameter information: Feedback information. Old value was 100, New value is 80 Maximum Observed Processes: 52 Information about VMS executable image Processing: Processing SYS$MANAGER:VMS$IMAGES_MASTER.DAT GBLPAGFIL parameter information: Override Information - parameter calculation has been overridden. The calculated value was 1024. The new value is 6024. GBLPAGFIL has been increased by 5000. GBLPAGFIL is not allowed to be less than 6024. GBLPAGES parameter information: Feedback information. Old value was 43300, New value is 50000 Peak used GBLPAGES: 36622 Global buffer requirements: 6024 GBLSECTIONS parameter information: Feedback information. Old value was 400, New value is 400 Peak used GBLSECTIONS: 294 Override Information - parameter calculation has been overridden. The calculated value was 350. The new value is 400. GBLSECTIONS is not allowed to be less than 400. LOCKIDTBL parameter information: Feedback information. Old value was 2943, New value is 3071 Current number of locks: 1853 Peak number of locks: 3200 LOCKIDTBL_MAX parameter information: Feedback information. Old value was 65535, New value is 65535 RESHASHTBL parameter information: Feedback information. Old value was 1024, New value is 1024 Current number of resources: 957 MSCP_LOAD parameter information: Override Information - parameter calculation has been overridden. The calculated value was 1. The new value is 0. MSCP_LOAD has been disabled by a hard-coded value of 0. MSCP_BUFFER parameter information: Feedback information. Old value was 128, New value is 128 MSCP server I/O rate: 0 I/Os per 10 sec. I/Os that waited for buffer space: 0 I/Os that fragmented into multiple transfers: 0 SCSCONNCNT parameter information: Feedback information. Old value was 5, New value is 5 Peak number of nodes: 1 Number of CDT allocation failures: 0 SCSRESPCNT parameter information: Feedback information. Old value was 300, New value is 300 RDT stall count: 0 SCSBUFFCNT parameter information: Feedback information. Old value was 512, New value is 512 CIBDT stall count: 0 NPAGEDYN parameter information: Feedback information. Old value was 686592, New value is 783360 Maximum observed non-paged pool size: 815616 bytes. Non-paged pool request rate: 47 requests per 10 sec. LNMSHASHTBL parameter information: Feedback information. Old value was 1024, New value is 1024 Current number of shareable logical names: 1194 ACP_DIRCACHE parameter information: Feedback information. Old value was 88, New value is 88 Hit percentage: 99% Attempt rate: 0 attempts per 10 sec. ACP_DINDXCACHE parameter information: Feedback information. Old value was 25, New value is 25 Hit percentage: 97% Attempt rate: 1 attempts per 10 sec. ACP_HDRCACHE parameter information: Feedback information. Old value was 88, New value is 106 Hit percentage: 98% Attempt rate: 17 attempts per 10 sec. ACP_MAPCACHE parameter information: Feedback information. Old value was 8, New value is 8 Hit percentage: 2% Attempt rate: 4 attempts per 10 sec. PAGEDYN parameter information: Feedback information. Old value was 521728, New value is 542208 Current paged pool usage: 304160 bytes. Paged pool request rate: 1 requests per 10 sec. PFRATL parameter information: Override Information - parameter calculation has been overridden. The calculated value was 0. The new value is 1. PFRATL has been disabled by a hard-coded value of 1. WSDEC parameter information: Override Information - parameter calculation has been overridden. The calculated value was 35. The new value is 19. WSDEC has been disabled by a hard-coded value of 19. MPW_LOLIMIT parameter information: Override Information - parameter calculation has been overridden. The calculated value was 120. The new value is 2100. MPW_LOLIMIT is not allowed to be less than 2100. MPW_HILIMIT parameter information: Override Information - parameter calculation has been overridden. The calculated value was 1310. The new value is 4500. MPW_HILIMIT is not allowed to be less than 4500. LONGWAIT parameter information: Override Information - parameter calculation has been overridden. The calculated value was 30. The new value is 10. LONGWAIT has been disabled by a hard-coded value of 10. WSMAX parameter information: Override Information - parameter calculation has been overridden. The calculated value was 8200. The new value is 12000. WSMAX is not allowed to be less than 12000. PROCSECTCNT parameter information: Override Information - parameter calculation has been overridden. The calculated value was 32. The new value is 40. PROCSECTCNT is not allowed to be less than 40. PQL_DWSEXTENT parameter information: Override Information - parameter calculation has been overridden. The calculated value was 400. The new value is 11000. PQL_DWSEXTENT is not allowed to be less than 11000. PQL_MWSEXTENT parameter information: Override Information - parameter calculation has been overridden. The calculated value was 2048. The new value is 11000. PQL_MWSEXTENT is not allowed to be less than 11000. VAXCLUSTER parameter information: Override Information - parameter calculation has been overridden. The calculated value was 1. The new value is 0. VAXCLUSTER has been disabled by a hard-coded value of 0. Page, Swap, and Dump file calculations Page and Swap file calculations. PAGEFILE1_SIZE parameter information: Feedback information. Old value was 45200, New value is 50500 Maximum observed usage: 25265 PAGEFILE1_SIZE will be modified to hold 50500 blocks PAGEFILE2_SIZE parameter information: Feedback information. Old value was 154000, New value is 194400 Maximum observed usage: 97175 PAGEFILE2_SIZE will be modified to hold 194400 blocks ** WARNING ** - The disk on which PAGEFILE2 resides would be over 95% full if it were modified to hold 194400 blocks. NODE22$DKA300:[SYSTEM_FILES]PAGEFILE.SYS will not be modified. NODE22$DKA300:[SYSTEM_FILES]PAGEFILE.SYS will remain at 154002 blocks. SWAPFILE1_SIZE parameter information: Feedback information. Old value was 15000, New value is 15000 Maximum observed usage: 14280 Override Information - parameter calculation has been overridden. The calculated value was 21400. The new value is 15000. SWAPFILE1_SIZE is not allowed to exceed 15000. SWAPFILE1 will not be modified. SWAPFILE2_SIZE parameter information: Feedback information. Old value was 50000, New value is 26300 Maximum observed usage: 1680 SWAPFILE2_SIZE will be modified to hold 26300 blocks ** WARNING ** - The disk on which SWAPFILE2 resides would be over 95% full if it were modified to hold 26300 blocks. NODE22$DKA300:[SYSTEM_FILES]SWAPFILE.SYS will not be modified. NODE22$DKA300:[SYSTEM_FILES]SWAPFILE.SYS will remain at 50001 blocks. Dumpfile calculations: No dump file modifications would have been made. Dumpfile will remain at 34116 blocks.

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