PMDF System Manager's Guide

PMDF uses a variety of internal tables to store configuration information. The sizes of these tables are specified by various option file options. If no specifications are given, default sizes are used. The result for small configurations can be wasted memory, while for large configurations PMDF may fail with a table overflow error.

The solution to these problems is to specify larger or smaller tables using the option file. The option file controls the size of the various tables very precisely; the result will be optimum memory usage with no overflows.

The CNBUILD (OpenVMS) or cnbuild (UNIX or NT) utility can be used to generate such specifications in the option file automatically. This use of CNBUILD or cnbuild does not mean that the configuration must be compiled. Either CNBUILD or cnbuild is quite capable of generating such an option file without generating a corresponding compiled configuration. The details of this use of CNBUILD or cnbuild are described below.

The size of the tables CNBUILD or cnbuild creates in the precompiled image is set before CNBUILD or cnbuild actually reads the configuration and alias files. As a result, small configurations generate images with lots of wasted space in them, while large configurations may exceed the default sizes of the tables and cause PMDF to report the infamous "no room in table" error message.

The solution to these problems is to generate a PMDF option file that describes the size of your configuration. The PMDF option file is described in Chapter 7. However, it is not necessary to know the format of that file; CNBUILD or cnbuild is capable of building an option file for you.

To generate an option file that specifies proper table sizes to hold your configuration, use the OpenVMS command,

$ PMDF CNBUILD/NOIMAGE/MAXIMUM/OPTION

or the UNIX command,

# pmdf cnbuild -noimage_file -maximum -option_file

or the NT command

C:\> pmdf cnbuild -noimage_file -maximum -option_file

Such a command will create a new PMDF option file with appropriate table sizes.

If you use a compiled configuration, you must then recompile your configuration. Consult Section 8.1 for details on compiling your configuration.

If you continue to get "no room in table" sorts of errors after using CNBUILD or cnbuild to resize your PMDF option file (and after then recompiling, if you use a compiled configuration), then you likely have a configuration syntax error that is causing PMDF to believe it sees spurious configuration entries; see some of the suggestions in Section 34.3.1 or Section 35.3.1 for possible syntax errors for which to check.

Note that you only have to resize your configuration when its size changes enough to warrant it. It is not necessary to do this when minor changes are made; the size information output by CNBUILD or cnbuild leaves room for moderate changes without resizing. The OpenVMS command,

$ PMDF CNBUILD/NOIMAGE/STATISTICS

or the UNIX command

# pmdf cnbuild -noimage_file -statistics

or the NT command

C:\> pmdf cnbuild -noimage_file -statistics

may be used to determine exactly how close your configuration really is to the current sizes set in the option file.