Document revision date: 15 July 2002

Example

The following example modifies the TTY_TIMEOUT parameter value in the VAX system parameter file:

$ SET DEFAULT SYS$SYSTEM $ RUN SYSGEN SYSGEN> USE CURRENT SYSGEN> SET TTY_TIMEOUT 3600 SYSGEN> WRITE CURRENT %OPCOM, 15-APR-2000 16:04:06.30, message from user SYSTEM %SYSGEN-I-WRITECUR, CURRENT system parameters modified by process ID 00160030 into file VAXVMSSYS.PAR SYSGEN> EXIT

15.8.4 Modifying Active Values with SYSGEN

Modifying active values immediately affects dynamic parameters by changing their values in memory. Appendix C of the OpenVMS System Management Utilities Reference Manual identifies dynamic parameters (as does the SYSGEN command SHOW/DYNAMIC). You cannot change values for nondynamic parameters while the system is running.

Modifying active values does not affect the current values in the system parameter file on disk. The next time you boot the system, the old current values are established as the active values.

If you set new active parameter values (by entering WRITE ACTIVE) and you want to use the new values for subsequent boot operations, you must write the new values to the current parameter file on disk by entering the WRITE CURRENT command, as explained in Section 15.8.3. If the parameters are not dynamic parameters, you must enter the WRITE CURRENT command and reboot the system.

When you change active parameters with SYSGEN, the operator communication manager (OPCOM) writes a message to the operator log and the operator console, unless you have changed the system message format with the DCL command SET MESSAGE.

Examples

1. The following example modifies the active value of the PFCDEFAULT parameter:

   $ SET DEFAULT SYS$SYSTEM $ RUN SYSGEN SYSGEN> SET PFCDEFAULT 127 SYSGEN> WRITE ACTIVE %OPCOM, 15-APR-2000 16:04:06.30, message from user SYSTEM %SYSGEN-I-WRITEACT, ACTIVE system parameters modified by process ID 00160030 SYSGEN> EXIT

2. The following example modifies the active value of the PFCDEFAULT parameter and also writes it to the Alpha system parameter file, so it will be used when the system reboots:

   $ SET DEFAULT SYS$SYSTEM $ RUN SYSGEN SYSGEN> SET PFCDEFAULT 127 SYSGEN> WRITE ACTIVE %OPCOM, 15-APR-2000 16:04:06.30, message from user SYSTEM %SYSGEN-I-WRITEACT, ACTIVE system parameters modified by process ID 00160030 SYSGEN> WRITE CURRENT %OPCOM, 15-APR-2000 16:04:06.30, message from user SYSTEM %SYSGEN-I-WRITECUR, CURRENT system parameters modified by process ID 00160030 into file ALPHAVMSSYS.PAR SYSGEN> EXIT

Creating a new parameter file has no effect on the running system. During a subsequent conversational boot operation, however, you can initialize the active system with the values of the new file.

How to Perform This Task

1. Invoke SYSGEN by entering the following commands:

   $ SET DEFAULT SYS$SYSTEM $ RUN SYSGEN

2. Enter a command in the following format to write a copy of a parameter file into SYSGEN's temporary workspace:

   USE file-spec

   
   where file-spec is the file specification for the parameter file to be used as a base. Modify the values in this file to create a new parameter file.

3. Enter commands in the following form to modify values as needed:

   SET parameter-name value

   
   where parameter-name specifies the name of the parameter to be changed, and value specifies the new value for the parameter.

4. Specify a command in the following format to write the values to a new parameter file:

   WRITE file-spec

   
   where file-spec is the file specification for the parameter file to be created.

5. Exit SYSGEN.

Examples

1. The following example creates a new version of the parameter file PARAMS.PAR with a new value for the TTY_TIMEOUT parameter:

   $ SET DEFAULT SYS$SYSTEM $ RUN SYSGEN SYSGEN> USE SYS$MANAGER:PARAMS.PAR SYSGEN> SET TTY_TIMEOUT 3600 SYSGEN> WRITE SYS$MANAGER:PARAMS.PAR SYSGEN> EXIT

2. The following example creates a file named SYS$SYSTEM:OURSITE.PAR, using the PARAMS.PAR file as a base:

   $ SET DEFAULT SYS$SYSTEM $ RUN SYSGEN SYSGEN> USE SYS$MANAGER:PARAMS.PAR SYSGEN> SET TTY_TIMEOUT 1000 SYSGEN> WRITE OURSITE.PAR SYSGEN> EXIT

With a conversational boot operation, you can modify the active parameter values in the following ways before the system boots:

Task	For More Information
Modify active values for individual parameters	Section 4.2.1
Initialize active values using values stored in a parameter file other than the default parameter file	Section 4.2.2
Reinitialize active values using default values	Section 4.4.1

At the end of the conversational boot, the default system parameter file is modified to store the new active parameter values.

OpenVMS Alpha Version 7.1 and later contains system parameters that control the operation of bus-addressable pool (BAP).

The CIPCA, CIXCD, KFMSB, and Qlogic 1020ISP adapters are some of the adapters that use bus-addressable pool to improve performance. BAP is a non-paged dynamic, physical-address-filtered memory pool used to overcome I/O bus and 32-bit adapter physical addressing limits.

The following table lists the system parameters that control BAP operation along with their default values:

System Parameter	Default Value
NPAG_BAP_MIN	0
NPAG_BAP_MAX	0
NPAG_BAP_MIN_PA	0
NPAG_BAP_MAX_PA	-1

The default values of these parameters allow the system to boot with any configuration. When AUTOGEN is run on a configured system, it resets these parameters to values that should enhance performance for the current system configuration.

If the system fails to boot after an installation, upgrade, or configuration change, and displays a message that refers to incorrect BAP parameters, Compaq recommends that you perform the following steps:

1. Reset the BAP parameters to the default values.
2. Reboot the system.
3. Allow the installation procedure to run AUTOGEN, or manually run AUTOGEN yourself.

A typical AUTOGEN with FEEDBACK command to set these parameters follows:

$ @SYS$UPDATE:AUTOGEN SAVPARAMS SETPARAMS FEEDBACK

If you prefer not to use this command because you want to adjust only the BAP parameters settings, use the following procedure:

1. Boot the system using the default BAP parameter values.
2. Manually run SYS$SYSTEM:AGEN$FEEDBACK.EXE:

   $ RUN SYS$SYSTEM:AGEN$FEEDBACK.EXE

3. Search SYS$SYSTEM:AGEN$FEEDBACK.DAT for the BAP_* system parameter values:

   $ SEARCH SYS$SYSTEM:AGEN$FEEDBACK.DAT "BAP_"

4. Run SYSGEN to set the following system parameters with the BAP values you obtained in Step 3:

   AGEN$FEEDBACK Data	System Parameter	Units
   BAP_MIN	NPAG_BAP_MIN	bytes
   BAP_MAX	NPAG_BAP_MAX	bytes
   BAP_MIN_PA	NPAG_BAP_MIN_PA	Mbytes 1
   BAP_MAX_PA	NPAG_BAP_MAX_PA	Mbytes 1

   ---

   ¹On OpenVMS Alpha systems prior to Version 7.2, the value of this parameter is specified in bytes.
   

   ---

The BAP allocation amount (specified by BAP_MIN and BAP_MAX) depends on the adapter type, the number of adapters, and the version of the operating system. The physical address range (specified by BAP_MIN_PA and BAP_MAX_PA) depends on the adapter type and the way the Galaxy logical partitions, if any, are defined.

Page, swap, and dump files are created by default. However, you should understand these files. In addition, you might want to change them to meet the needs of your site.

Information Provided in This Chapter

This chapter describes the following tasks:

Task	Section
Displaying information about page and swap files	Section 16.3
Calculating appropriate sizes for files	Section 16.4
Minimizing dump file size when disk space is insufficient	Section 16.5
Writing a dump file on a system disk with multiple paths or shadow set members	Section 16.6
Writing the dump file to a device other than the system disk	Section 16.7
Using SDA to analyze the contents of a crash dump	Section 16.8
++Using SDA CLUE commands to obtain and analyze summary crash dump information	Section 16.9
+Using CLUE to obtain historical information about crash dumps	Section 16.10
Saving the contents of the system dump file after a system failure	Section 16.11
Copying dump files to tape or disk	Section 16.12
Freeing dump information from the page file	Section 16.13
Installing page and swap files	Section 16.14
Removing page, swap, and dump files	Section 16.15
Creating and modifying page, swap, and dump files	Section 16.16
Controlling access to process dumps	Section 16.17.2

This chapter explains the following concepts:

Concept	Section
Understanding dump files	Section 16.1
Understanding page and swap files	Section 16.2
Understanding the order of information in a selective system dump	Section 16.5.1
++Understanding SDA CLUE	Section 16.9.1
+Understanding CLUE	Section 16.10.1
Understanding process dumps	Section 16.17

When the operating system detects an unrecoverable error or an inconsistency within itself that causes the system to fail, it writes the contents of the error log buffers, processor registers, and memory into the system dump file, overwriting its previous contents.

The contents of error log buffers are also written to the error log dump file. The error log dump file is provided so that the system can be updated on reboot to include error log entries that were created but not written at the time of a system crash.

System Dump File

When writing the system dump file, the system displays console messages and information about the error or inconsistency. The last message tells you that the dump file was successfully written.

Console messages and the system dump file are important sources of information in determining the cause of a system failure. Use the contents in the following ways:

• Use the System Dump Analyzer utility (SDA) to analyze the contents of the dump and determine the cause of a failure.
• On Alpha systems, use SDA CLUE commands to obtain and analyze summary dump file information.
• On VAX systems, use CLUE to obtain historical information from system dump files.
• Contact your Compaq support representative, indicating that you have made a copy of the contents of the system dump.

The default system dump file, SYS$SPECIFIC:[SYSEXE]SYSDUMP.DMP, is created during installation. (You do not need a system dump file to run the operating system. However, you must have a system dump file to diagnose system crashes.) AUTOGEN automatically determines an appropriate size for the system dump file for your hardware configuration and system parameters. Refer to Section 16.5 for information about minimizing system dump file size if disk space is insufficient.

For special configurations or varying work loads, you can change the size of the system dump file. For information, see Section 16.16.1. You can write the system dump file on a disk other than the system disk. This is referred to as dump off system disk (DOSD). For more information, see Section 16.7.

Error Log Dump File

AUTOGEN creates the error log dump file during installation; its size depends on your configuration and system parameters. Error log dump files on VAX and Alpha systems have the following differences:

• On Alpha systems, the error log dump file is called SYS$ERRLOG.DMP; it is located on the system disk. When an operator initiates a shutdown, the system writes the contents of error log buffers to the error log dump file and not to the system dump file. Thus, the last system crash dump is not overwritten.
• On VAX systems, the error log dump file is called SYSDUMP.DMP. How the system handles this file depends on whether you are using dump off system disk (DOSD):
  • With DOSD, error logs are written to a stub error log dump file, SYSDUMP.DMP, on the system disk. Also, both the error logs and system memory are written to the SYSDUMP.DMP file on the DOSD disk.
  • Without DOSD, both the error log and system memory are written to the SYSDUMP.DMP file on the system disk.
  
  On VAX systems with or without DOSD, the last system crash dump is always overwritten when an operator initiates a shutdown.

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