[OpenVMS documentation]
[Site home] [Send comments] [Help with this site] [How to order documentation] [OpenVMS site] [Compaq site]
Updated: 11 December 1998

OpenVMS System Manager's Manual


Previous Contents Index

15.6.2 DOSD Requirements on VAX Systems

On VAX systems, writing the DOSD has the following requirements:

Note

To restore error log buffers when the system is rebooted after a system crash, the error logs must be saved on the system disk. For this purpose, AUTOGEN creates a SYSDUMP.DMP file on the system disk; the file is large enough to contain the maximum size of error log buffers.

15.7 Using SDA to Analyze the Contents of a Crash Dump

The System Dump Analyzer utility (SDA) lets you interpret the contents of the system dump file to investigate the probable causes of the crash. For information about analyzing a crash dump, refer to the OpenVMS VAX System Dump Analyzer Utility Manual or the OpenVMS Alpha System Dump Analyzer Utility Manual.

If your system fails, make a copy of the system dump file written at the time of the failure and contact your Compaq support representative. For information about copying the system dump file, see Section 15.11.

15.8 Using SDA CLUE Commands to Analyze Crash Dump Files (Alpha Only)

SDA CLUE (Crash Log Utility Extractor) commands automate the analysis of crash dumps and maintain a history of all fatal bugchecks on a standalone system or cluster. You can use SDA CLUE commands in conjunction with SDA to collect and decode additional dump file information not readily accessible through standard SDA. You can also use SDA CLUE with Dump Off System Disk (DOSD) to analyze a system dump file that resides on a disk other than the system disk.

15.8.1 Understanding CLUE (Alpha Only)

On Alpha systems, SDA is automatically invoked by default when you reboot the system after a system failure. To better facilitate crash dump analysis, SDA CLUE commands automatically capture and archive summary dump file information in a CLUE listing file.

A startup command procedure initiates commands that:

The CLUE HISTORY command adds a one-line summary entry to a history file and saves the following output from SDA CLUE commands in the listing file:

The contents of this CLUE list file can help you analyze a system failure.

If these files accumulate more space than the threshold allows (default 5000 blocks), the oldest files are deleted until the threshold limit is reached. This can also be customized using the CLUE$MAX_BLOCK logical name.

To inhibit the running of CLUE at system startup, define the logical CLUE$INHIBIT in the SYLOGICALS.COM file as /SYS TRUE.

It is important to remember that CLUE$nodename_ddmmyy_hhmm.LIS contains only an overview of the crash dump and does not always contain enough information to determine the cause of the crash. If you must do an in-depth analysis of the system crash, Compaq recommends that you always use the SDA COPY command to save the dump file.

15.8.2 Displaying Data Using SDA CLUE Commands (Alpha Only)

Invoke CLUE commands at the SDA prompt as follows:


SDA> CLUE CONFIG

CLUE commands provide summary information of a crash dump captured from a dump file. When debugging a crash dump interactively, you can use SDA CLUE commands to collect and decode some additional information from a dump file, which is not easily accessible through standard SDA. For example, CLUE can quickly provide detailed XQP summaries.

You can also use CLUE commands interactively on a running system to help identify performance problems.

You can use all CLUE commands when analyzing crash dumps; the only CLUE commands that are not allowed when analyzing a running system are CLUE CRASH, CLUE ERRLOG, CLUE HISTORY, and CLUE STACK.

Refer to OpenVMS Alpha System Dump Analyzer Utility Manual for more information about using SDA CLUE commands.

15.8.3 Using SDA CLUE with Dump Off System Disk (Alpha Only)

Dump off system disk (DOSD) allows you to write the system dump file to a device other than the system disk. For SDA CLUE to be able to correctly find the dump file to be analyzed after a system crash, you need to perform the following steps:

  1. Modify the command procedure SYS$MANAGER:SYLOGICALS.COM to add the system logical name CLUE$DOSD_DEVICE to point to the device where the dump file resides. You need to supply only the physical or logical device name without a file specification.
  2. Modify the command procedure SYS$MANAGER:SYLOGICALS.COM to mount systemwide the device where the dump file resides. Otherwise, SDA CLUE cannot access and analyze the dump file.

In the following example, the dump file is placed on device $3$DUA25, with the label DMP$DEV. You need to add the following commands to SYS$MANAGER:SYLOGICALS.COM:


$mount/system/noassist $3$dua25: dmp$dev dmp$dev
$define/system clue$dosd_device dmp$dev

15.9 Using CLUE to Obtain Historical Information About Crash Dumps (VAX Only)

On VAX systems, the Crash Log Utility Extractor (CLUE) displays the contents of a crash history file. By examining the contents of the crash history file, you can understand and resolve the issues responsible for failures (crashes), and you might also obtain other useful data.

15.9.1 Understanding CLUE (VAX Only)

The crash history file, which is created and updated by CLUE, contains key parameters from crash dump files. Unlike crash dumps, which are overwritten with each system failure and are therefore typically available only for the most recent failure, the crash history file is a permanent record of system failures.

After a system fails and physical memory is copied to the crash dump file, CLUE automatically appends the relevant parameters to the file CLUE$OUTPUT:CLUE$HISTORY.DATA when the system is restarted. The remainder of this section describes how you can use CLUE to display the data it has collected; reference information about CLUE is available in the OpenVMS System Management Utilities Reference Manual.

Note

The history file typically grows by about 10 to 15 blocks for each entry. You can limit the number of entries in the binary file by defining the logical name CLUE$MAX_ENTRIES to be the maximum number desired. When this number is reached, the oldest entries are deleted from the history file.

By default, operator shutdowns are recorded in the history file. You can exclude information from operator shutdowns in the history file by defining the logical name CLUE$EXCLUDE_OPERS as being TRUE, for example by including the following line in SYS$MANAGER:SYSTARTUP_VMS.COM:


$ DEFINE /SYSTEM CLUE$EXCLUDE_OPERS TRUE 

15.9.2 Displaying Data Using CLUE (VAX Only)

To display data using CLUE, you must first define the following symbol:


$ CLUE :== $CLUE 

After defining the symbol, you can use CLUE to display information by entering the following command:


$ CLUE/DISPLAY
CLUE_DISPLAY> 

At the CLUE_DISPLAY> prompt, you can issue commands to perform the following actions:

For more information about CLUE commands, refer to the OpenVMS System Management Utilities Reference Manual.

15.10 Saving the Contents of the System Dump File After a System Failure

If the system fails, it overwrites the contents of the system crash dump file and the previous contents are lost. For this reason, ensure that your system automatically analyzes and copies the contents of the system dump file each time the system reboots.

On Alpha systems, SDA is invoked by default during startup, and a CLUE list file is created. Generated by a set sequence of commands, the CLUE list file contains only an overview of the crash and might not provide enough information to determine the cause of the crash. Compaq, therefore, recommends that you always copy the system dump file.

Refer to the OpenVMS Alpha System Dump Analyzer Utility Manual for information about modifying your site-specific command procedure to execute additional commands such as SDA COPY upon startup after a system failure.

On VAX systems, modify the site-specific startup command procedure SYSTARTUP_VMS.COM so that it invokes the System Dump Analyzer utility (SDA) when the system is booted.

Be aware of the following facts:

Example

The SDA command COPY in the following example saves the contents of the file SYS$SYSTEM:SYSDUMP.DMP and performs some analysis of the file:


$ ! 
$ !      Print dump listing if system just failed 
$ ! 
$ ANALYZE/CRASH_DUMP SYS$SYSTEM:SYSDUMP.DMP 
    COPY SYS$SYSTEM:SAVEDUMP.DMP        ! Save system dump file 
    SET OUTPUT DISK1:SYSDUMP.LIS        ! Create listing file 
    READ/EXECUTIVE                      ! Read in symbols for kernel 
    SHOW CRASH                          ! Display crash information 
    SHOW STACK                          ! Show current stack 
    SHOW SUMMARY                        ! List all active processes 
    SHOW PROCESS/PCB/PHD/REG            ! Display current process 
   EXIT 
$ SET FILE/NOBACKUP SYS$SYSTEM:SAVEDUMP.DMP 
 
 

15.11 Copying System Dump Files to Tape or Disk

If your system fails, make a copy of the contents of the system dump file and contact your Compaq support representative. You can use the Backup utility (BACKUP) to create save sets containing system dump files on magnetic tape or disk. However, when using BACKUP to copy system dump files, you must specify the /IGNORE=(NOBACKUP,INTERLOCK) qualifier for the following reasons:

For more information about using BACKUP, see Chapter 10. For information about BACKUP commands, see the BACKUP section in the OpenVMS System Management Utilities Reference Manual.

Compaq recommends that you use the following procedure to copy your system dump file:

  1. Use the SDA command COPY to make a copy of the system dump file.
  2. Use BACKUP to save that copy on tape or disk.

This procedure avoids issues with BACKUP qualifiers and reduces the amount of data written to tape or disk because the SDA command COPY copies only blocks in the system dump file that are actually used.

15.12 Freeing Dump Information from the Page File

If you use SYS$SYSTEM:PAGEFILE.SYS to store a system crash dump, you must later free the space occupied by the system dump for use by the pager. If you do not, your system might hang because of insufficient paging space.

Section 15.1 explains when you might use the page file to store a system crash dump.

15.12.1 Freeing Dump Information on VAX and Alpha Systems

This section contains instructions for freeing dump information from the page file on VAX and Alpha systems.

How to Perform This Task on VAX Systems

On VAX systems, perform the following steps:

  1. Invoke the System Dump Analyzer utility (SDA), specifying PAGEFILE.SYS as the target:


    $ ANALYZE/CRASH_DUMP SYS$SYSTEM:PAGEFILE.SYS
    

  2. Enter the SDA command COPY in the following format to copy the dump from SYS$SYSTEM:PAGEFILE.SYS to another file:

    COPY dump_filespec 
    


    For example, to copy the system dump file off the system disk to a file called SAVEDUMP.DMP on DISK$USER5, enter the following command:


    SDA> COPY DISK$USER5:[DUMPS]SAVEDUMP.DMP
    

  3. Enter the EXIT command to exit SDA.
  4. Include the SDA commands entered in steps 1 and 2 in the site-specific startup command procedure SYSTARTUP_VMS.COM to free page space each time the system reboots.

Alternatively, to free the pages in the page file that are taken up by the dump without having to copy the dump elsewhere, enter the ANALYZE/CRASH_DUMP/RELEASE command. This command immediately releases the pages to be used for system paging, effectively deleting the dump. Note that this command does not allow you to analyze the dump before deleting it.

Example

The following commands, added to the SYSTARTUP_VMS.COM command procedure, copy the contents of the page file to a file named SAVEDUMP.DMP:


$ ANALYZE/CRASH_DUMP SYS$SYSTEM:PAGEFILE.SYS 
  COPY DISK$USER5:[DUMPS]SAVEDUMP.DMP 
  EXIT 
$ SET FILE/NOBACKUP SYS$SYSTEM:SAVEDUMP.DMP 
 
 

How to Perform This Task on Alpha Systems

On Alpha systems, as described in the OpenVMS Alpha System Dump Analyzer Utility Manual, SDA is automatically invoked by default when the system is rebooted after a system failure.

To automatically save the system dump file, perform the following steps:

  1. Create a SYS$$MANAGER:SAVEDUMP.COM file; for example:


    ! 
    ! SDA command file, to be executed as part of the system 
    ! bootstrap from within CLUE.  Commands in this file can 
    ! be used to save the dump file after a system bugcheck, and 
    ! to execute any additional SDA command. 
    ! 
    READ/EXEC               ! Read in the executive images' symbol tables 
    COPY SAVEDUMP.DMP       ! Copy and save system dump file 
    SHOW STACK              ! Display the stack 
    ! 
    

  2. To point to your site-specific file, add a line such as the following one to the file SYS$MANAGER:SYLOGICALS.COM:


    $ DEFINE/SYSTEM CLUE$SITE_PROC SYS$MANAGER:SAVEDUMP.COM
    

    In this example, the site-specific file is named SAVEDUMP.COM.

If the logical CLUE$INHIBIT has been defined, and SDA has not been automatically invoked during system startup, the pages in the page file that are taken up by the dump can be released using the ANALYZE/CRASH_DUMP/RELEASE command. This command immediately releases the pages to be used for system paging, effectively deleting the dump. Note that this command does not allow you to analyze the dump before deleting it.

For a discussion of logical names used by CLUE, refer to OpenVMS Alpha System Dump Analyzer Utility Manual.

15.12.2 Usage Notes for Freeing Information on VAX and Alpha Systems

Because a system dump file can contain privileged information, protect copies of dump files from world read access.

To prevent the system from backing up the complete contents of the file, assign the NOBACKUP attribute to the file with the DCL command SET FILE/NOBACKUP.

Although you can also use the DCL command COPY to copy a dump file, Compaq recommends that you use the SDA command COPY because SDA COPY performs the following actions:

15.13 Installing Page and Swap Files

The system automatically installs the primary page and swap files located in SYS$SYSTEM. However, other page and swap files are not automatically installed. For this reason, if you create secondary page and swap files, you must also install them with the System Generation utility (SYSGEN). Note that SYSGEN INSTALL commands perform a different function than Install utility (INSTALL) commands.

15.13.1 Installing Interactively

  1. Invoke SYSGEN by entering the following command:


    $ RUN SYS$SYSTEM:SYSGEN
    

  2. Enter the SYSGEN command INSTALL as follows:
    For page files, use the following format:

    INSTALL file-spec/PAGEFILE 
    


    For example:


    SYSGEN> INSTALL DUA2:[PAGE_SWAP]PAGEFILE_1.SYS/PAGEFILE
    

    For swap files, use the following format:

    INSTALL file-spec/SWAPFILE 
    


    For example:


    SYSGEN> INSTALL DUA2:[PAGE_SWAP]SWAPFILE_1.SYS/SWAPFILE
    

  3. To make sure the files are installed each time the system boots, edit SYS$MANAGER:SYPAGSWPFILES.COM to add the commands you entered in step 2. For more information, see Section 15.13.2.

Example

The following example installs page and swap files interactively:


$ RUN SYS$SYSTEM:SYSGEN
SYSGEN> INSTALL DUA2:[PAGE_SWAP]PAGEFILE_1.SYS/PAGEFILE
SYSGEN> INSTALL DUA2:[PAGE_SWAP]SWAPFILE_1.SYS/SWAPFILE


Previous Next Contents Index

[Site home] [Send comments] [Help with this site] [How to order documentation] [OpenVMS site] [Compaq site]
[OpenVMS documentation]

Copyright © Compaq Computer Corporation 1998. All rights reserved.

Legal
6017PRO_071.HTML