HP OpenVMS Systems Documentation

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OpenVMS VAX Version 7.3
Upgrade and Installation Manual

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Appendix H
Small Capacity System Disks

This appendix describes some methods you can use to manage small capacity system disks. Some specific recommendations are also included for installing or upgrading to OpenVMS VAX Version 7.3 and DECwindows Motif for OpenVMS VAX Version 1.2-6 on an RZ24 or RA80 system disk. (These recommendations also apply to earlier versions of the DECwindows Motif for OpenVMS VAX layered product.)

Note that you can use the methods described in this appendix to free disk space on any space-constrained system.

H.1 Limited Space Support

As the OpenVMS VAX operating system and associated layered products continue to develop and mature, their sizes have grown. Previously acceptable system disk devices might now have insufficient capacity for the desired computing environment. Support for added features, conformance to standards, addition of online documentation, and especially, support for a graphical user environment (specifically, DECwindows Motif for OpenVMS VAX) have contributed to this growth. Although a single-user workstation system might be perceived as entry level, it does, in fact, have an increased need for system disk capacity to handle the desired graphical environment.

H.1.1 Limited Space Support Option

In the past, when the OpenVMS VAX operating system grew too large for a specific disk type, that disk was no longer supported as a system device. The OpenVMS VAX Version 7.3 operating system and the DECwindows Motif for OpenVMS VAX layered product cannot fit, in total, on an RZ24 disk device.

However, to preserve the investment in some user configurations, a limited space support option has been introduced that allows the RZ24 to continue to be used as a system disk but with some features removed. For the most part, these features include new online documentation, programming examples, and programming support files. The most important mechanisms used to provide this environment are the OpenVMS VAX and DECwindows tailoring facilities, VMSTAILOR and DECW$TAILOR. (For more information about these facilities, see Chapter 10.)

The limited space support option means that, although the disk (in this case, the RZ24) is supported as a system device, you must take some explicit action to remove or not to install some portions of the product so the remainder fits. This option gives small, resource-constrained system users a choice between investing in new hardware or continuing with existing hardware but with (possibly) reduced capabilities.

H.1.2 Configurations Affected

The RZ24 disk is now too small for the full OpenVMS VAX Version 7.3 and DECwindows Motif for OpenVMS VAX kits, regardless of the user's configuration. Slightly larger disk devices need to be closely monitored, depending on the system environment and user configuration.

The general disk space guideline for OpenVMS VAX plus DECwindows Motif for OpenVMS VAX Version 1.2-6 is a system disk of at least 300 megabytes (or about 614,400 disk blocks). For nonworkstation, single-user systems, this guideline can be reduced to 150 to 200 megabytes because DECwindows support is not necessary. For timesharing systems, a larger disk is usually necessary due to the need for many layered products and applications. For OpenVMS Cluster systems, a larger system disk capacity is also usually required. Refer to the Compaq OpenVMS Cluster Software, SPD 29.78.19 for details.

For specific information about disk space requirements and supported system disks, refer to the Compaq OpenVMS Operating System for Alpha and VAX, Version 7.3 SPD 25.01.63.

While the absolute minimum disk space requirements can make base system support available, layered products, applications, and user files usually make it necessary to manage even large capacity system disks carefully. Therefore, some of the following techniques and ideas can be useful for a broader range of users than can be listed by hardware type.

H.1.3 Dealing with a Small System Disk

You can solve small system disk configuration problems in three ways:

  • Upgrade your hardware to a larger capacity disk device.
  • Add additional hardware disk devices (one or more) to the system and redistribute the software contents.
  • Reduce the software contents on the existing disk device.

Upgrading hardware might have the highest monetary cost, but has the benefits of a full environment and the simplest and fastest upgrade mechanism. Adding additional hardware (or using existing extra hardware) can require less money, but requires more time and effort for setting up and maintaining the environment. Reducing the software contents requires the lowest capital expense but, by necessity, removes some features, documentation, or capabilities.

If your major constraint is fiscal, you might want to investigate the tailoring recommendations first. If time or simplicity are more important, you might want to purchase a larger system disk.

H.2 Tailoring Considerations

Most of this appendix describes the mechanisms for reducing the software contents on the existing disk device, mostly by tailoring. There are also some hints for multiple disk systems. There is nothing specific to recommend for upgrading the hardware device, except that moving up in a single large increment is much more effective than several smaller ones.

The target device in the following sections is the RZ24 disk, which has 209 megabytes of disk space. However, you can use these methods on any system that is tight on system disk space.

H.2.1 Configuration Goals

The basic configuration goal for the limited space support option is for an environment that is not used for programming. Typically, this is a system with a few user applications or a turnkey system. It is possible to build a viable system with a single programming language environment (notably, the C language); however, the space used for this support and for the compiler reduces the amount of available user space.

There are some mechanisms and techniques common to any space-constrained system both for installing new systems and for upgrading existing systems. One of the most important considerations is to reduce the disk space consumption of the normal, ongoing system environment before doing an upgrade or as soon as possible during or after an installation. Some methods for accomplishing this are discussed in Section H.5 and in Section H.6.

Note that, during an upgrade or installation, there is a period of time when the windowing software is likely to be unavailable. This means that, on a workstation, your monitor functions only as an operator console, and you cannot use screen-oriented editors.

H.2.2 Controlling the Size of Dump, Page, and Swap Files

One of the primary things to control is the sizing of the dump, page, and swap files in AUTOGEN. The tailoring facilities automatically use AUTOGEN to reboot the system, adjusting anything that the tailoring might have affected. Because AUTOGEN normally includes existing disk space in calculating the sizes for these files, unexpected results can occur when tailoring removes some files and AUTOGEN increases the size of others. Fixing the size of these files by adding appropriate lines to the file SYS$SYSTEM:MODPARAMS.DAT will prevent this from occurring during an upgrade or after an installation (and, possibly, while installing layered products).

The following values are suggested as generous for an upgrade:

PAGEFILE = 38000
SWAPFILE = 13500

If your system has been running successfully with smaller values, use those instead.

If your windowing system is unavailable, you cannot use a screen-oriented editor to add these lines to the SYS$SYSTEM:MODPARAMS.DAT file. You can use the COPY command to add lines to the end of the text file as follows:

newparam1 = value1 [Return]
newparam2 = value2 [Return]


To be able to use the delete key more effectively when typing input to the console, set the operator terminal to be a scope (assuming it is not a hardcopy device). To set the console terminal to be a scope, enter the following command:


H.2.3 Make a Backup Copy of Your System Disk

It is important to make a backup copy of your system disk before any system software upgrade. When tailoring and system environment options must be used to fit the required software on the device, it is even more important to make a backup copy before you begin and at major milestones during the procedure. This gives you a fallback to a last good position in the event that a subsequent step produces undesired side effects (especially when tailoring software off of the disk) or fails because you unexpectedly ran out of disk space.

H.2.4 Analyze the System Disk

The space used on the system disk might include files that have been only partially deleted (usually, because they were still open when an attempt was made to delete them). To recover this space, enter the following command:


Continue to use the ANALYZE/DISK/REPAIR command after every reboot or before each major step to be sure that all free blocks are available for the upgrade procedure to use.

H.2.5 Tailoring Options

The installation and upgrade procedures (for both OpenVMS VAX Version 7.3 and DECwindows Motif for OpenVMS VAX) let you select optional software to install or upgrade only by save set. The tailoring facilities are capable of finer granularity and can usually select files in smaller groups within the save sets.

In the case of DECW$MOTIF_TAILOR, the save sets and tailoring groups are the same. Additionally, DECW$MOTIF_TAILOR can only tailor off. To add files, you must either use the installation or upgrade procedures or use the OpenVMS Backup utility (BACKUP) manually to select the desired files. For the VMSTAILOR and DECW$TAILOR utilities, the tailorable options are subsets of the installation and upgrade save sets and can be tailored either on or off. If there is sufficient space to take an entire save set, it is usually faster to select it during the procedure and then tailor off the undesired pieces, rather than tailor them on later.

If you performing an upgrade and have a large area of user application files or a large database that is not part of the OpenVMS VAX operating system or DECwindows Motif for OpenVMS VAX layered product but resides on the system disk, it might be convenient to back up that data to a separate piece of media, delete it from the system disk before the upgrade, and then restore it after the upgrade. The blocks can be used in the interim, and you can save time and effort in the tailoring and upgrade processes.

You can decrease the time needed to perform the tailoring and upgrade tasks by disabling the high-water mark on the system disk. To disable the high-water mark, enter the following command:


Depending on the system security you require, you might want to leave the high-water mark permanently disabled. Otherwise, you can restore it by entering the following command:


H.3 Installing OpenVMS VAX and DECwindows Motif for OpenVMS VAX

In general, installing OpenVMS VAX Version 7.3 and the latest version of DECwindows Motif for OpenVMS VAX is easier than doing an upgrade because there are no user files on the disk when you perform the installation. However, because the total size of the two kits is larger than the capacity of the RZ24 disk, you cannot select some options and you might have to do some tailoring.

H.3.1 Installing OpenVMS VAX Version 7.3

By itself, the entire OpenVMS VAX Version 7.3 distribution kit fits on the RZ24 system disk. So, the easiest approach might be to select both the library and optional save sets, then use the VMSTAILOR and DECW$TAILOR utilities to increase the free space before installing the DECwindows Motif for OpenVMS VAX layered product.

If you plan to run DECnet for OpenVMS, be sure to select the library save set. If you do not perform system programming or BLISS programming, do not have an LPA11 device, do not need any of the OpenVMS example files, and do not need the UETP facility, you can choose not to select the optional save set during the installation. The BLISS support in the optional save set (approximately 7000 blocks) and the examples (over 8500 blocks) are two of the largest single areas that you can easily tailor off.

You might choose not to install the Help Message (MSGHLP) database because this option is also very large (about 10,000 blocks). Or, you can select it at the expense of other tailorable options later (or at the expense of reduced user capacity). Or you can install the Help Message database and then customize it to remove messages for facilities that you do not use. (Refer to the OpenVMS System Manager's Manual, Volume 1: Essentials for details about how to do this.)

Once the OpenVMS VAX installation is complete, set up the dump file as required. It is preferable not to have a dump file at all or to use the paging file as described in Section H.5.1. Also, set fixed sizes for the page and dump files so that AUTOGEN does not continually resize them as you proceed with tailoring and installing the DECwindows Motif for OpenVMS VAX layered product. When your environment is complete, you can remove the fixed sizes to allow AUTOGEN to calculate appropriate sizes based on the final space on the disk.

To fit the operating system on an RZ24 disk and have sufficient space to add some layered product or application packages and have user space remaining, you can generally support, at most, one programming language and no online examples or manuals. Use the VMSTAILOR and DECW$TAILOR utilities to remove software you do not need.

H.3.2 Installing DECwindows Motif for OpenVMS VAX

Depending on the options and setup of your system, you might have sufficient space to install the entire DECwindows Motif for OpenVMS VAX kit. However, it is likely that you again will need to remove support for all but one programming language and not include the examples. Because the programming support save sets for each language are large, choose only the support for languages you really need. In the case of the example files, you might want to install them if you have the space required, and then tailor them off once you have perused them or copied them to another area.

Remember to use the ANALYZE/DISK/REPAIR command to recover any lost space from partially deleted files.

H.4 Upgrading OpenVMS VAX and DECwindows Motif for OpenVMS VAX

The following sections describe how to upgrade to OpenVMS VAX Version 7.3 and DECwindows Motif for OpenVMS VAX Version 1.2-6 from an OpenVMS VAX Version 6.1 or 6.2 (or higher) system running an older version of DECwindows Motif for OpenVMS VAX. (Note that Version 1.2-4 is the minimum version of DECwindows Motif for OpenVMS VAX that you can run on OpenVMS VAX Version 7.3.)

This option requires the most attention and extra tailoring consideration because the disk blocks used by the DECwindows Motif for OpenVMS VAX layered product cannot be used during the OpenVMS VAX upgrade procedure. This means that you might not be able to select even the library save set during the upgrade and that you will need to tailor on portions of it (most notably, the DECnet support).

Depending on your configuration, it might be necessary to tailor off DECwindows Motif for OpenVMS VAX and then reinstall it following the upgrade.

H.4.1 Upgrading to OpenVMS VAX Version 7.3

Before beginning the upgrade procedure, prepare the system environment --- notably the dump, page, and swap files (see Section H.2.2) --- and remove as many excess files from the system disk as possible. Use the tailoring facilities to remove files that will be replaced or obsoleted by the upgrade procedure. This is a good way to get the necessary space (48,950 blocks) to start the upgrade but probably does not contribute to the final additional capacity required.

Tailor off all the OpenVMS programming files, examples, and miscellaneous utilities and any DECwindows Motif for OpenVMS VAX support that is not required. Before upgrading the operating system, keep, at most, one language support option, and do not keep any DECwindows Motif for OpenVMS VAX examples unless you have sufficient space to get at least the OpenVMS VAX required and library save sets directly in the upgrade.

If you have sufficient space after tailoring to allow both the OpenVMS VAX required and library save sets to be selected, then the upgrade will include DECnet support and DECwindows Motif for OpenVMS VAX will start normally after the upgrade.

If you cannot select the library save set, the lack of DECnet support will likely keep DECwindows Motif for OpenVMS VAX from starting on your system (at which point you will have only the operator window on your workstation). You can then tailor on the DECnet support to get DECwindows Motif for OpenVMS VAX running again. After you have DECwindows Motif for OpenVMS VAX running, tailoring on any other pieces you might not have already acquired from either the library or optional save sets will be easier.

Compaq recommends that you not take the optional Help Message utility (unless you install it on an alternate device). You want to choose the DECwindows device support if you are upgrading a workstation.

Remember to use the ANALYZE/DISK/REPAIR command to clean up any partially deleted files.

H.5 Managing Single or Small System Disk Systems

The primary goal for this type of environment is to reduce the system disk block usage incurred by the OpenVMS VAX system during normal operation. Both dynamic usage and static requirements can be reduced in various ways. Some system processing overhead can also be reduced or eliminated in this manner, along with a corresponding reduction in system disk I/O.

H.5.1 System Dump File

One of the best mechanisms for reducing the total block overhead of the system is to carefully define the usage of the system dump file. Normally, this is configured as a separate file, SYS$SYSTEM:SYSDUMP.DMP, to which the contents of memory are written after a detected system failure. Depending on your system requirements, you might be able to reduce or eliminate this disk usage.

One effective technique is to use part of the system paging file, SYS$SYSTEM:PAGEFILE.SYS, as a temporary dump file, so that the space used for dump files is not permanently reserved and gets used only in the event of a crash. To do this, you need to modify some system parameters in SYS$SYSTEM:MODPARAMS.DAT and delete the actual SYSDUMP.DMP file if it exists. This method is most effective for systems having small or medium memory sizes.

Alternately, you might set the DUMPSTYLE parameter to use the selective dump mechanism to reduce the size of the dump file. This method is typically used for large memory systems that do not need to preserve the entire memory contents in the event of a system failure. Instead of using selective dumps to the paging file, keep a separate, but smaller, SYSDUMP.DMP file.

If you have no need to preserve dump files or are running in a very stable environment, you might want to clear the DUMPBUG parameter to avoid all dump processing and not write a dump file on failure.

H.5.2 Using PAGEFILE.SYS for the Dump File

To use the system paging file as a dump file, add the following lines to the SYS$SYSTEM:MODPARAMS.DAT file:

DUMPBUG = 1  ! Enable system dumps (default)
SAVEDUMP = 1  ! Keep dump in pagefile until analysis
DUMPFILE = 0  ! Disallow AUTOGEN to create or size dump file

Then delete the SYSDUMP.DMP file by entering the following command:


Because the system currently has the file open, the delete command does not physically remove the file until the system is shut down and rebooted. Use the AUTOGEN facility to reboot the system. When it has rebooted, enter the following command to clean up and finish the deletion of the file (and any others that were in a similar state):


After a system failure that writes dump information to the page file, you can analyze the data by entering the following command:


When your analysis is complete, you can free the pages to be used for paging once again by entering the following command:


For more information about the system dump file, refer to the OpenVMS VAX System Dump Analyzer Utility Manual.

H.5.3 Decompressing Libraries

The OpenVMS help libraries (as well as some programming libraries) are distributed in a compressed format. You can use the SYS$UPDATE:LIBDECOMP.COM procedure to decompress the libraries all at once or individually. For a small system disk, it is almost never worth the extra disk blocks consumed to decompress these libraries. The cost of leaving them compressed is a longer access time when you use them.

If you frequently use help or an individual programming library, it might be worthwhile to individually decompress those libraries. If you only infrequently use help or do not mind the slower response time of the libraries in compressed form, leave them compressed.

H.5.4 Disabling Log File Creation

Depending on your environment, there might be system jobs that create log files of no concern to you or that contain more information than you need.

Unless you are a network manager or experiencing network problems, you probably do not need to log network events. By not logging network events, you can save disk space, a process slot, and some memory in the running system. To disable network logging, enter the following commands:


You need to enter these commands only once; they become permanent unless you reset the DECnet logging information.

To reduce the logging information for other tasks (such as OPCOM, Accounting, Security Auditing, Network Monitor Event Listener, and system-created batch log files), you need to add some commands to your system-specific startup command file, SYS$MANAGER:SYSTARTUP_VMS.COM (previously called SYSTARTUP_V5.COM).

The following is an example SYSTARTUP_VMS.COM command file for a single-user workstation:

$ SET NOON     ! Continue thru any problems.
$ DEFINE/USER SYS$COMMAND _OPA0:  ! Disable some events from
$ REPLY/DISABLE=(NETWORK,CLUSTER,SECURITY) !  using the operator window.
$ SET TERM/SCOPE/PERM _OPA0:   ! If windows do not start, use as scope.
$ SET AUDIT/ALARM -    ! Log interesting audit events.
    PURGE SYS$MANAGER:ACCOUNTNG.DAT/KEEP=4 ! Purge old accounting info
    PURGE SYS$MANAGER:OPERATOR.LOG/KEEP=4 ! Purge old operator info
$ ENABLE AUTOSTART/QUEUES   ! Provide resources for autostart queues
$ START/QUEUE SYS$BATCH    ! Start a batch queue
$! ...  add other system specific and layered product commands here ...

You might have an environment that can function with even less information than that shown in the example. For example, to disable the operator log file, use REPLY/NOLOG, or to disable accounting, use SET ACCOUNTING/DISABLE. For more information about using these commands, refer to the OpenVMS DCL Dictionary.

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