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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.

Using the Page File to Store System Crash Dumps explains when you might use the page file to store a system crash dump.

Freeing Dump Information on VAX, Alpha, and I64 Systems  

This section contains instructions for freeing dump information from the page file on VAX, Alpha, and I64 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_filespecFor 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 and I64 Systems

On Alpha and I64 systems, as described in the OpenVMS System Analysis Tools 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$MANAGER:SAVEDUMP.COM file; for example:
    !
    ! SDA command file, to be executed as part of the system
    ! bootstrap from within CLUE.  Commands in this file can
    ! be used to save the dump file after a system bugcheck, and
    ! to execute any additional SDA command.
    !
    READ/EXEC               ! Read in the executive images' symbol tables
    SHOW STACK              ! Display the stack
    COPY SAVEDUMP.DMP       ! Copy and save system dump file
    !
  2. To point to your site-specific file, add a line such as the following one to the file SYS$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 System Analysis Tools Manual .

Usage Notes for Freeing Dump Information on VAX, Alpha, and I64 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, HP recommends that you use the SDA command COPY because SDA COPY performs the following actions:


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