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Creating and Modifying Page, Swap, and Dump Files  



For performance or disk space reasons, you might want to create system page, swap, and dump files on disks other than the system disk. (Error log dump files, however, must remain on the system disk.)

The following sections explain how to perform this task:

Method For More Information
Using AUTOGEN (recommended method)
Using AUTOGEN (Recommended Method)
Using SWAPFILES.COM (for primary files only)
Using SWAPFILES.COM
Using SYSGEN
Using SYSGEN

Using AUTOGEN (Recommended Method)  

You can direct AUTOGEN to create new system page, swap, and dump files by adding symbols to MODPARAMS.DAT to specify the name, location, and size of new files to be created and then running AUTOGEN. Before performing this task, you should understand AUTOGEN and its parameter file MODPARAMS.DAT. For more information about when to use AUTOGEN, see Understanding the AUTOGEN Command Procedure. See AUTOGEN Parameter File (MODPARAMS.DAT) for information about MODPARAMS.DAT.

AUTOGEN automatically calculates appropriate sizes for system page, swap, and dump files. It also modifies the files to the appropriate sizes and installs them. You can control sizes calculated by AUTOGEN by defining symbols in the file MODPARAMS.DAT. For more information, see Controlling the Size of System Page, Swap, and Dump Files in MODPARAMS.DAT.

How to Perform This Task

To change the sizes of system page, swap, and dump files, execute AUTOGEN in two passes as follows:

Controlling the Location of System Page, Swap, and Dump Files  

Add the following symbols to MODPARAMS.DAT to specify the names and locations of the page and swap files to be created:

Definition For Page Files For Swap Files For Dump Files
File name and location
PAGEFILEn_NAME = "file-spec"
SWAPFILEn_NAME = "file-spec"
DUMPFILE_DEVICE = "device"

where:

Controlling the Size of System Page, Swap, and Dump Files in MODPARAMS.DAT  

You can add information to the AUTOGEN parameter file MODPARAMS.DAT to control the sizes that AUTOGEN calculates for system page, swap, and dump files. If you do not supply system file size information in MODPARAMS.DAT, AUTOGEN performs default size calculations for page, swap, and dump files.

You can define symbols in MODPARAMS.DAT to specify either of the following items:

Size to Be Specified For More Information
Total desired size for all page or swap files on a system (not valid for the system dump files)
Symbols for Controlling the Total Size of Page, Swap, System Dump, or Error Log Dump File Space
Sizes for individual page, swap, or dump files
Symbols for Controlling the Size of Individual Page and Swap Files


NoteYou cannot specify sizes for both total and individual files. AUTOGEN issues a warning if conflicting symbol definitions exist in MODPARAMS.DAT.

For page and swap files, AUTOGEN generally manipulates the primary files SYS$SYSTEM:PAGEFILE.SYS and SYS$SYSTEM:SWAPFILE.SYS only if you have no other page and swap files. If you have secondary files, AUTOGEN manipulates the secondary files and excludes primary files. However, in some instances, AUTOGEN might modify the size of the primary page and swap files.

On VAX systems, for system dump files, AUTOGEN manipulates the size of only one file: the system dump file on the system disk if no DUMPFILE_DEVICE is given, or the system dump file on the specified device if DUMPFILE_DEVICE is specified.

On VAX systems, AUTOGEN always creates a minimal SYSDUMP.DMP file on the system disk for error log buffers if DUMPFILE_DEVICE is specified.

On Alpha and I64 systems, AUTOGEN manipulates only the size of the error log dump file on the system disk.

If you do not want AUTOGEN to change the sizes of the primary files, specify the following symbols in MODPARAMS.DAT:

PAGEFILE = 0
SWAPFILE = 0
DUMPFILE = 				0
ERRORLOGDUMP = 0 ! Alpha and I64
These symbols direct AUTOGEN to ignore the primary page, swap, and dump files when calculating sizes.

If the creation or extension of a system page, swap, or dump file would cause the target disk to become more than 95 percent full, AUTOGEN issues a warning and does not perform the operation.

On Alpha and I64 systems, however, the 95 percent rule does not apply to the error log dump file, SYS$ERRLOG.DMP. This file is created if the disk can hold it.

You can use AUTOGEN to create a page, swap, or dump file that is smaller than the current version of the file. After you have booted and begun using the new file, remember to use the DCL command PURGE to reclaim the disk space from the old version of the file.

To determine the current sizes of installed page and swap files, enter the DCL command SHOW MEMORY/FILES. If you increased the size of any of these files and have not rebooted, this command displays the original sizes. Use the DIRECTORY command to determine the size of dump files.


NoteAUTOGEN does not change file sizes if you specify a value of 0 or a value that is within 10 percent of the current size.

Symbols for Controlling the Total Size of Page, Swap, System Dump, or Error Log Dump File Space lists the symbols you can define in MODPARAMS.DAT to control the total size of page file, swap file, system dump file, or error log dump file space space.

Table 4   Symbols for Controlling the Total Size of Page, Swap, System Dump, or Error Log Dump File Space
Operation Page File Symbol Swap File Symbol Dump File Symbol Error Log File Symbol
To define the total amount of space
PAGEFILE = n1
SWAPFILE = n
DUMPFILE = n
ERRORLOGDUMP = n
To increase total size
ADD_PAGEFILE = n
ADD_SWAPFILE = n
ADD_DUMPFILE = n
ADD_ERRORLOGDUMP = n
To specify maximum total size
MAX_PAGEFILE = n
MAX_SWAPFILE = n
MAX_DUMPFILE = n
MAX_ERRORLOGDUMP = n
To specify minimum total size
MIN_PAGEFILE = n
MIN_SWAPFILE = n
MIN_DUMPFILE = n
MIN_ERRORLOGDUMP = n

Symbols for Controlling the Size of Individual Page and Swap Files lists the symbols you can define in MODPARAMS.DAT to control the size of individual files.

Table 5   Symbols for Controlling the Size of Individual Page and Swap Files
Operation Page File Symbol2 Swap File Symbol
To specify file size
PAGEFILEn_SIZE = block-size
SWAPFILEn_SIZE = block-size
To increase file size
ADD_PAGEFILEn_SIZE = block-size
ADD_SWAPFILEn_SIZE = block-size
To specify maximum file size
MAX_PAGEFILEn_SIZE = block-size
MAX_SWAPFILEn_SIZE = block-size
To specify minimum file size
MIN_PAGEFILEn_SIZE = block-size
MIN_SWAPFILEn_SIZE = block-size

Examples

  1. The following line in MODPARAMS.DAT specifies that all page file space should total 100,000 blocks:
    PAGEFILE = 100000
    If you had only a primary page file, the resulting size of that file would be 100,000 blocks. If you had multiple page files, the difference between the total current size and the total new size would be spread across secondary files. For example, if you specified PAGEFILE = 100000, the changed page file sizes would be as follows:

    File Original Size (in Blocks) Resulting Size (in Blocks)
    Primary page file
    10,000
    10,000
    Secondary page file 1
    30,000
    45,000
    Secondary page file 2
    30,000
    45,000

  2. To direct AUTOGEN to set the primary page file size to 10,000 blocks, use the symbol definition:
    PAGEFILE1_SIZE = 10000
  3. To direct AUTOGEN to create a new secondary swap file named PAGED$:[PAGESWAP]SWAPFILE.SYS that holds 30,000 blocks, use the symbol definitions:
    SWAPFILE2_NAME = "PAGED$:[PAGESWAP]SWAPFILE.SYS"
    MIN_SWAPFILE2_SIZE = 30000

Using SWAPFILES.COM  

HP recommends that you use AUTOGEN to change sizes of system page, swap, and dump files. However, you can use the command procedure SYS$UPDATE:SWAPFILES.COM to change the size of primary system page, swap, and dump files. SWAPFILES.COM shows you the current size of the system page, swap, and dump files before you change the sizes.

If you change the sizes of system page, swap, or dump files, you must edit MODPARAMS.DAT to specify the new sizes, as explained in Controlling the Size of System Page, Swap, and Dump Files in MODPARAMS.DAT. If you do not specify the new sizes in MODPARAMS.DAT, AUTOGEN resizes the files next time it runs.

The procedure displays the sizes of the current system page, swap, and dump files in SYS$SYSTEM, and the amount of space remaining on the system disk. It then allows you to enter new sizes, or keep the existing sizes for these files. If you specify a size that is larger than that of an existing file, the procedure automatically extends the size of a page or dump file. If you specify a smaller size for a system page, swap, or dump file, a new version of the file is created.

How to Perform This Task

  1. Enter the following command to invoke the command procedure:
    $ @SYS$UPDATE:SWAPFILES.COM
    The system displays the current files found in SYS$SYSTEM and their sizes. For example:
    Current file sizes are:
     
    Directory SYS$SYSROOT:[SYSEXE]
     
    PAGEFILE.SYS;1    16384
    SYSDUMP.DMP;1      4128
    SWAPFILE.SYS;1     3072
     
    Total of 3 files, 23584 blocks.
     
    There are 128741 available blocks on SYS$SYSDEVICE.
  2. In response to the following prompt, type the desired size, in blocks, for the page file. To keep the same size, press Return:
    Enter new size for page file:
  3. In response to the following prompt, type the desired size, in blocks, for the dump file. To keep the same size, press Return:
    Enter new size for system dump file: 
  4. In response to the following prompt, type the desired size, in blocks, for the swap file. To keep the same size, press Return:
    Enter new size for swap file: 
  5. Shut down and reboot the system to use the new files.
  6. After the system reboots, purge obsolete copies of the files. Do not delete the old files until the system reboots.
  7. Edit MODPARAMS.DAT to include the new file sizes, as explained in Controlling the Size of System Page, Swap, and Dump Files in MODPARAMS.DAT. If you do not specify the new sizes in MODPARAMS.DAT, AUTOGEN will automatically resize the files the next time it runs.

Example

$ @SYS$UPDATE:SWAPFILES.COM
To leave a file size at its current value type a
carriage return in response to its size prompt.
Current file sizes are:
 
Directory SYS$SYSROOT:[SYSEXE]
 
PAGEFILE.SYS;1    100000
SYSDUMP.DMP;1      28000
SWAPFILE.SYS;1     33000
 
Total of 3 files, 161000 blocks.
 
There are 128741 available blocks on SYS$SYSDEVICE.
 
Enter new size for page file: [Return] 
Enter new size for system dump file: 30000
%SYSGEN-I-EXTENDED, SYS$SYSROOT:[SYSEXE]SYSDUMP.DMP;1 extended
Enter new size for swap file: [Return] 

 
***********************************************************************
*  Please reboot in order for the new files to be used by the system. *
*  After rebooting, purge obsolete copies of the files.               *
*  DO NOT delete the old files until after the reboot.                *
***********************************************************************

Using SYSGEN  

HP recommends that you use AUTOGEN to create and change page, swap, and dump files. AUTOGEN invokes the System Generation utility (SYSGEN) to create or change the files. However, in an emergency, you can use SYSGEN to directly change the size of page, swap and dump files. For example, if you see that page file space is becoming dangerously low, you might use SYSGEN to quickly add page file space to prevent the system from hanging.


NoteVAX:

The system parameters SWPFILCNT and PAGFILCNT limit the number of swap and page files that the system installs. Refer to the HP OpenVMS System Management Utilities Reference Manual for more information.

Alpha and I64:

OpenVMS Alpha and I64 support a maximum of 254 page and or swap files on a system. The system parameters SWPFILCNT and PAGFILCNT are not used on Alpha and I64 systems.


How to Perform This Task

  1. Determine the location and appropriate size of the files. For information, see Manually Calculating Appropriate Sizes for Dump, Page, and Swap Files.
  2. Invoke SYSGEN and enter the CREATE command in the following format:CREATE file-spec/SIZE=block-countwhere:

    file-spec specifies the full file specification.

    block-count specifies the size of the file in blocks.

    If the file you specify already exists and the size you specify is larger than the existing file, the command extends the existing file. If the file you specify already exists and the size you specify is smaller than the existing file, the command creates a new file of the specified size.

    For example, the following command extends the existing, smaller primary page file PAGEFILE.SYS:
    SYSGEN> CREATE PAGEFILE.SYS/SIZE=100000
    For more information about the SYSGEN command CREATE, refer to the SYSGEN section in the HP OpenVMS System Management Utilities Reference Manual: M--Z.
    NoteFrequent file creation and deletion can cause the free space on a disk to become severely fragmented. SYSGEN issues a HEADERFULL warning message if it determines that the creation or extension of a system file would cause that file to become fragmented enough to render the system unbootable. If this occurs, HP recommends that you back up and restore your system disk to consolidate the free space on the volume into one contiguous area. For more information, see the HP OpenVMS System Manager's Manual, Volume 1: Essentials.

    After you restore the disk, retry the SYSGEN operation. When SYSGEN issues a warning message, the file might be somewhat larger, but not as large as the value specified in the CREATE command.


  3. Use the following table to determine if you should reboot to use the new or modified file:

    Type Change Reboot Required?
    Primary page, swap, system dump, or error log dump file.3
    New file
    Yes

    Extended file
    Yes
    Secondary page or swap file
    New file
    No4

    Extended file
    Yes
    Alternate (DOSD) dump file (Alpha and I64)
    New file
    No

    Extended file
    No
    Alternate (DOSD) dump file (VAX)
    New file
    Yes

    Extended file
    Yes

  4. If you create a new version of the file, purge the old version after the system reboots.
  5. Add commands to the site-specific startup command procedure SYPAGSWPFILES.COM to make sure the files are installed each time the system boots. For instructions, see Installing Page and Swap Files.
  6. If you do not want AUTOGEN to resize the files according to its calculations, edit MODPARAMS.DAT to specify the sizes of these files. Follow the instructions in Controlling the Size of System Page, Swap, and Dump Files in MODPARAMS.DAT.

Example

The commands in the following example extend the existing files PAGEFILE.SYS, SWAPFILE.SYS, and SYSDUMP.DMP to the specified sizes:

$ RUN SYS$SYSTEM:SYSGEN
SYSGEN> CREATE PAGEFILE.SYS/SIZE=100000
%SYSGEN-I-EXTENDED, SYS$SYSROOT:[SYSEXE]PAGEFILE.SYS;1 extended
SYSGEN> CREATE SWAPFILE.SYS/SIZE=30000
%SYSGEN-I-EXTENDED, SYS$SYSROOT:[SYSEXE]SWAPFILE.SYS;1 extended
SYSGEN> CREATE SYSDUMP.DMP/SIZE=33000
%SYSGEN-I-EXTENDED, SYS$SYSROOT:[SYSEXE]SYSDUMP.DMP;1 extended
SYSGEN> EXIT   

Footnotes
1n is the total size, in blocks. If n is 0, the corresponding AUTOGEN section is skipped. For page and swap files, if n is not 0 and no secondary files exist, AUTOGEN applies the value to primary files. If n is not 0, and secondary files exist, AUTOGEN applies any change evenly across all secondary page or swap files but, in most cases, does not change primary files. For dump files, if n is not 0, AUTOGEN applies the value to the dump file on the system disk if no DUMPFILE_DEVICE is given or the dump file on the specified device if a DUMPFILE_DEVICE is given.
2For n, specify an integer that indicates the page or swap file. Refer to the primary page and swap files by specifying a value of 1 for n; refer to subsequent files by specifying increasingly higher integer values for n. For example, to refer to a secondary page or swap file, specify a value of 2 for n. For block-size, specify the size in blocks.
3Primary page, swap, and dump files are SYS$SPECIFIC:[SYSEXE]PAGEFILE.SYS, SWAPFILE.SYS, SYSDUMP.DMP; and SYS$ERRLOG.DMP.
4Although rebooting the system is unnecessary, you must install secondary files before the system can use them. For more information, see Installing Page and Swap Files.

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