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For more information on the SYSGEN SHOW command and qualifiers, see the SYSGEN section of the OpenVMS System Management Utilities Reference Manual.
Example
The following example uses SYSGEN to show the current values of all TTY system parameters:
$ RUN SYS$SYSTEM:SYSGEN SYSGEN> USE CURRENT SYSGEN> SHOW/TTY
Parameters in use: Current(1) Parameter Name Current Default Min. Max. Unit Dynamic -------------- ------- ------- ------- ------- ---- ------- (2) (3) (4) (5) (6) (7) TTY_SCANDELTA 10000000 10000000 100000 -1 100Ns TTY_DIALTYPE 0 0 0 255 Bit-Encode TTY_SPEED 15 15 1 16 Special TTY_RSPEED 0 0 0 16 Special TTY_PARITY 24 24 0 255 Special TTY_BUF 80 80 0 65535 Characters TTY_DEFCHAR 402657952 402657952 0 -1 Bit-Encode TTY_DEFCHAR2 135178 4098 0 -1 Bit-Encode TTY_TYPAHDSZ 78 78 0 -1 Bytes TTY_ALTYPAHD 2048 200 0 32767 Bytes TTY_ALTALARM 750 64 0 -1 Bytes TTY_DMASIZE 64 64 0 -1 Bytes D (8) TTY_CLASSNAME "TTY" "TTY" "AA" "ZZ" Ascii TTY_SILOTIME 8 8 0 255 Ms TTY_TIMEOUT 3600 900 0 -1 Seconds D TTY_AUTOCHAR 7 7 0 255 Character D SYSGEN>
SYSGEN displays the following information:
Caution
Parameter values modified with the System Generation utility (SYSGEN) will be overridden by the AUTOGEN command procedure. To keep parameter modifications made with SYSGEN, edit the file SYS$SYSTEM:MODPARAMS.DAT as explained in Section 14.5.1 to specify the new parameter values.
Note
Although you can modify system parameter values with SYSGEN, Digital recommends you use AUTOGEN. For more information, see Section 14.5.If you cannot use AUTOGEN, Digital recommends you use the System Management utility (SYSMAN) to modify system parameters. For more information, see Section 14.7.
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-1996 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
Caution
Parameter values modified with SYSGEN will be overridden by the AUTOGEN command procedure. To keep parameter modifications made with SYSGEN, edit the file SYS$SYSTEM:MODPARAMS.DAT as explained in Section 14.5.1 to specify the new parameter value.
Note
Although you can modify system parameter values with SYSGEN, Digital recommends you use AUTOGEN or the System Management utility (SYSMAN). For more information, see Section 14.7.
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 14.8.3. 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
$ SET DEFAULT SYS$SYSTEM $ RUN SYSGEN SYSGEN> SET PFCDEFAULT 127 SYSGEN> WRITE ACTIVE %OPCOM, 15-APR-1996 16:04:06.30, message from user SYSTEM %SYSGEN-I-WRITEACT, ACTIVE system parameters modified by process ID 00160030 SYSGEN> EXIT
$ SET DEFAULT SYS$SYSTEM $ RUN SYSGEN SYSGEN> SET PFCDEFAULT 127 SYSGEN> WRITE ACTIVE %OPCOM, 15-APR-1996 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-1996 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
$ SET DEFAULT SYS$SYSTEM $ RUN SYSGEN
USE file-spec
SET parameter-name value
WRITE file-spec
Caution
Parameter values modified with SYSGEN are overridden by the AUTOGEN command procedure. To keep parameter modifications made with SYSGEN, edit the file SYS$SYSTEM:MODPARAMS.DAT as explained in Section 14.5.1 to specify the new parameter values.
Examples
$ 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
$ SET DEFAULT SYS$SYSTEM $ RUN SYSGEN SYSGEN> USE SYS$MANAGER:PARAMS.PAR SYSGEN> SET TTY_TIMEOUT 1000 SYSGEN> WRITE OURSITE.PAR SYSGEN> EXIT
Note
Although you can modify system parameters with a conversational boot, Digital recommends you use AUTOGEN or the System Management utility (SYSMAN). For more information, see Section 14.5 and Section 14.7.Use a conversational boot only to change isolated system parameters temporarily or in an emergency. For example, during a system upgrade, you would use a conversational boot to modify STARTUP_P1 to use a minimum startup.
Remember that if you change a value and do not add the changed value to the AUTOGEN parameter file MODPARAMS.DAT, AUTOGEN will overwrite the value the next time AUTOGEN executes.
With a conversational boot operation, you can modify the active parameter values in the following ways before the system boots:
| Task | For More Information |
|---|---|
| Modify active values for individual parameters | Section 4.2.1 |
| Initialize active values using values stored in a parameter file other than the default parameter file | Section 4.2.2 |
| Reinitialize active values using default values | Section 4.4.1 |
At the end of the conversational boot, the default system parameter file is modified to store the new active parameter values.
Caution
Parameter values modified with a conversational boot will be overridden by the AUTOGEN command procedure. To keep parameter modifications made with a conversational boot, edit the file SYS$SYSTEM:MODPARAMS.DAT as explained in Section 14.5.1 to specify the new parameter values.
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 15.3 |
| Calculating appropriate sizes for files | Section 15.4 |
| Minimizing dump file size when disk space is insufficient | Section 15.5 |
| Using SDA to analyze the contents of a crash dump | Section 15.6 |
| ++Using SDA CLUE commands to obtain and analyze summary crash dump information | Section 15.7 |
| +Using CLUE to obtain historical information about crash dumps | Section 15.8 |
| Copying dump files to tape or disk | Section 15.9 |
| Writing the dump file to a device other than the system disk | Section 15.10 |
| Saving the contents of the system dump file after a system failure | Section 15.11 |
| Freeing dump information from the page file | Section 15.12 |
| Installing page and swap files | Section 15.13 |
| Removing page, swap, and dump files | Section 15.14 |
| Creating and modifying page, swap, and dump files | Section 15.15 |
This chapter explains the following concepts:
| Concept | Section |
|---|---|
| Understanding dump files | Section 15.1 |
| Understanding page and swap files | Section 15.2 |
| Understanding the order of information in a selective system dump | Section 15.5.1 |
| ++Understanding SDA CLUE | Section 15.7.1 |
| +Understanding CLUE | Section 15.8.1 |
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.
On Alpha systems, 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.
Caution
Be sure to wait until you see the termination message before using the console terminal to halt the system. If you do not wait, your system might not save a complete system dump file.
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:
The default system dump file, SYS$SPECIFIC:[SYSEXE]SYSDUMP.DMP, is furnished as an empty file in the operating system distribution kit. (You do not need a system dump file to run the operating system. However, you must have a system dump file to diagnose system crashes.) AUTOGEN automatically determines an appropriate size for the system dump file for your hardware configuration and system parameters. Refer to Section 15.5 for information on minimizing system dump file size if disk space is insufficient.
For special configurations or varying work loads, you can change the size of the system dump file. For information, see Section 15.15.1. You can place the system dump file on a disk other than the system disk. For more information, see Section 15.10.
Error Log Dump File (Alpha Only)
On Alpha systems, the error log dump file,
SYS$SPECIFIC:[SYSEXE]SYS$ERRLOG.DMP, is not provided on the
distribution kit; AUTOGEN creates this file during installation.
AUTOGEN automatically determines the appropriate size of the error log dump file for your configuration and system parameters. The error log dump file must always be on the system disk.
The operating system uses the latest version of SYS$SYSTEM:SYSDUMP.DMP to store system crash dumps. If SYSDUMP.DMP does not exist in SYS$SYSTEM, the operating system uses the system page file, SYS$SYSTEM:PAGEFILE.SYS, overwriting the contents of that file.
If the SAVEDUMP system parameter is set, the crash dump is retained in PAGEFILE.SYS when the system is booted. If SAVEDUMP is clear, the system uses the page file for paging; any dump written to the page file is lost.
If you use SYS$SYSTEM:PAGEFILE.SYS to capture system crash dumps, you should later free the space occupied by the dump for use in system paging, with either of the following methods:
For detailed instructions, see Section 15.12.
Include the appropriate commands in the SYSTARTUP_VMS.COM startup command procedure to free dump information from the page file each time the system reboots.
Caution
Be careful when using the page file for selective dumps. Selective dumps use up all available space. If your page file is small, selective dump information might fill the entire page file, leaving no space for paging during system boot. This can cause the system to hang during reboot.
The two types of system dumps are physical and selective. Table 15-1 defines physical and selective system dumps. Table 15-3 compares the information available in physical and selective system dump files.
| Type | Description |
|---|---|
| Physical dump | Writes the entire contents of physical memory to the system dump file. To ensure a useful physical dump, the system dump file must be large enough to contain all of physical memory. |
| Selective dump | Stores those portions of memory most likely to be useful in crash dump analysis. A selective system dump is useful when disk space is not available to hold all of physical memory. |
Requirements for Creating a Useful System Dump
The following requirements must be met for the operating system to write a useful system dump file:
BACKUP Considerations
A system dump file has the NOBACKUP attribute; therefore, the Backup utility (BACKUP) does not copy the file unless you use the qualifier /IGNORE=NOBACKUP when invoking BACKUP. When you use the SDA COPY command to copy the system dump file to another file, the operating system does not automatically set the new file to NOBACKUP. If you want to set the NOBACKUP attribute on the copy, use the SET FILE command with the /NOBACKUP qualifier as described in the OpenVMS DCL Dictionary.
Security Considerations
By default, SYS$SYSTEM:SYSDUMP.DMP is protected against world access. Because a system dump file can contain privileged information, you should keep this level of protection on system dump files. Similarly, when you copy system dump files using the System Dump Analyzer utility (SDA) as explained in Section 15.11 and Section 15.12, be sure to protect the copy from world read access. For more information on file protection, see the OpenVMS Guide to System Security.
As part of memory management, the operating system makes efficient use of physical memory by moving information between physical memory and files stored on disk. The system does this in two ways: paging and swapping. Table 15-2 defines these and related terms.
| Term | Definition |
|---|---|
| Paging | A memory management operation that provides the efficient use of physical memory allotted to a process. Paging moves infrequently used portions of a process workspace out of physical memory to a file. For more information on paging, see the OpenVMS Performance Management. |
| Page file | The file to which the system writes paged portions of memory. Your distribution kit includes a page file named SYS$SYSTEM:PAGEFILE.SYS. If necessary, you can use SYS$SYSTEM:PAGEFILE.SYS in place of the system crash dump file. For more information, see Section 15.1.1. |
| Swapping | A memory management operation that provides the efficient use of physical memory available for the entire system. Swapping moves the entire workspace of a less active process out of physical memory to a file. For more information on swapping, see the OpenVMS Performance Management. |
| Swap file | The file to which the system writes swapped portions of memory. Your distribution kit includes a swap file named SYS$SYSTEM:SWAPFILE.SYS. |
| Primary page and swap files | The default page and swap files provided with your distribution kit. These files are named SYS$SYSTEM:PAGEFILE.SYS and SYS$SYSTEM:SWAPFILE.SYS. |
| Secondary page and swap files | Additional page and swap files that you might create for performance or disk space reasons. If you kept the primary page and swap file on the system disk, the system uses the space in the secondary files for paging and swapping in addition to the space in the primary page and swap files. For information on creating secondary page and swap files, see Section 15.15. |
Installing Files
Page and swap files must be installed before the system can use them. The system automatically installs the latest versions of SYS$SYSTEM:PAGEFILE.SYS and SWAPFILE.SYS during startup. If you create secondary page and swap files, you must make sure the system installs them during startup. For more information on installing page and swap files, see Section 15.13.
File Sizes and Locations
AUTOGEN automatically determines appropriate sizes for the files for your hardware configuration and system parameters. For special configurations or varying work loads, you might want to change the size of the page or swap file. For information, see Section 15.15.1.
6017P048.HTM OSSG Documentation 22-NOV-1996 14:22:26.70
Copyright © Digital Equipment Corporation 1996. All Rights Reserved.