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sys_attrs(5)
NAME
  sys_attrs - introduction to kernel subsystem attributes used for
  configuration and tuning

DESCRIPTION
  The operating system kernel is built from many mandatory and optional
  subsystems. If you are logged into the root account, the following command
  lists the subsystems included in the kernel for your system:

       # /sbin/sysconfig -s

  The majority of the kernel subsystems have sets of attributes whose values
  control different aspects of subsystem configuration. These attributes
  reside in the /etc/sysconfigtab database.  You can examine the names, the
  current settings, and (if applicable) the minimum, and maximum settings of
  attributes for a particular subsystem by using the /sbin/sysconfig command.
  The -q option followed by the subsystem name displays attribute names and
  current settings. The -Q option followed by the subsystem name displays
  minimum and maximum settings and the kinds of operations permitted on the
  attribute (Configurable (at boot time), Reconfigurable (at run time), Query
  only). In the Common Desktop Environment (CDE), you can run the
  dxkerneltuner application to get the same information.

  You can use the dxkerneltuner application or the /sbin/sysconfig -r command
  to dynamically change attributes for a kernel subsystem. For settings that
  persist across system boots, attribute values are applied through a
  stanza-formatted file that is specified as an argument to the sysconfigdb
  command.

  See dxkerneltuner(8), sysconfig(8), and sysconfigdb(8) for more information
  about your options for configuring kernel subsystems.

  The following subsystems must be included when the kernel is built:

    ·  Configuration Manager (cm)

    ·  Generic Kernel (generic)

    ·  Interprocess Communication (ipc)

    ·  Process (proc)

    ·  Virtual File System (vfs)

    ·  Virtual Memory (vm)

  A kernel also includes a processor-specific subsystem whose name is an
  internal code for a particular processor. Processor-specific subsystems
  typically have no attributes, are not modified directly by users, and are
  not documented.

  Other kernel subsystems are technically optional, although a kernel almost
  always includes quite a few optional subsystems in order for a system to be
  useful. For information on the attributes for a particular subsystem, refer
  to the reference page for that subsystem. The names of these reference
  pages adhere to the format sys_attrs_subsystem-name. For example, to see
  the reference page that lists and describes attributes for the generic
  subsystem, you can type man sys_attrs_generic at the system command line.

  For guidelines on changing kernel subsystem attributes to improve system
  performance, see the System Configuration and Tuning manual. Any discussion
  about changing attributes for reasons other than tuning is located in the
  appropriate administration or program debugging manual.

  You can adjust some subsystem attribute values at run time. If so, the
  attribute descriptions mention that fact. To make it easy for you to locate
  these attributes when scanning lists, an asterisk (*) also precedes the
  names of these attributes.

NOTES
  When changing kernel attributes, keep in mind the following points:

    ·  Many attributes should not be touched.

       A relatively small number of the attributes listed by the sysconfig
       utility or dxkerneltuner application should actually be changed and,
       if they are changed, only as part of the system configuration and
       tuning tasks done by an experienced system or network administrator.
       The setting of most subsystem attributes should be done indirectly
       through system and network setup applications or be automatically
       adjusted by the kernel. This fact is very important to remember
       because attribute settings can have complex interrelationships with
       one another, requiring (in some cases) careful manipulation of an
       entire set of attributes rather than only one.  Furthermore, default
       settings of some attributes should never be touched, except by support
       personnel or by an administrator acting on instructions from support
       personnel or patch kit documentation.

    ·  A few attributes that are reconfigurable at run time should not be
       modified manually.

       Most of the attributes that are modifiable at run time have been
       implemented this way for ease of system tuning. Others are modifiable
       at run time only because of a software requirement and should not be
       changed manually. In general, do not change the default value of any
       system attribute manually unless the system documentation or your
       support representative provides directions for changing it.

    ·  Attributes are volatile.

       System attributes are volatile, such that their effect, values, and
       existence can change from one release to another. This volatility is
       related to changes in kernel algorithms that make the system more
       self-adjusting, changes in the internal buffers and queues used by
       kernel software, the need to support new platforms and device
       architectures, and so forth. For this reason, attribute settings that
       worked well on one version of the operating system or on a different
       hardware platform should not be simply carried forward after a system
       upgrade. Doing so might not deliver the results you expect and might
       even degrade system performance. It is recommended that system
       upgrades be tested with default attribute settings in place and then
       tuned, as necessary, according to the most current system
       documentation. The best procedure to use when tuning is to tune one
       subsystem at a time. Check the performance effects of your attribute
       changes in each subsystem before changing attributes in another
       subsystem.

    ·  Some attribute names contained hyphens in previous releases and now
       contain underscores.  However, when processing an attribute name, the
       system accepts underscores and hyphens as equivalent characters.

    ·  The /usr/sys/conf/param.c file is obsolete.

       Some attributes used to have corresponding parameters in the
       /usr/sys/conf/param.c file, which system administrators were
       accustomed to editing directly in Tru64 UNIX Version 4.0D and prior
       releases. The operating system software changed over the course of
       subsequent releases to reduce its reliance on the
       /usr/sys/conf/param.c file. Starting with Tru64 UNIX Version 5.1A, the
       /usr/sys/conf/param.c file is not created after subsets are installed.
       A /usr/sys/conf/param.c file may still be used to apply configuration
       parameters to third-party driver modules that require it; however, the
       /etc/sysconfigtab database is now the recommended repository for
       configuration and tuning values that are applied to the operating
       system at boot time.

SEE ALSO
  Commands: dxkerneltuner(8), sysconfig(8), sysconfigdb(8)

  Others: sys_attrs_cm(5), sys_attrs_generic(5), sys_attrs_ipc(5),
  sys_attrs_proc(5), sys_attrs_vfs(5), sys_attrs_vm(5)

  This list includes only the reference pages for technically required
  subsystems. The number of subsystems that can be configured in a kernel is
  very large, so all system attribute reference pages are not listed here.

  System Configuration and Tuning

  System Administration

  Network Administration: Connections

  Network Administration: Services

  Kernel Debugging

Index for Section 5

Alphabetical listing for S

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