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GNOP(8)                   BSD System Manager's Manual                  GNOP(8)

NAME
     gnop -- control utility for NOP GEOM class

SYNOPSIS
     gnop create [-v] [-f failprob] [-o offset] [-s size] [-S secsize] dev ...
     gnop configure [-v] [-f failprob] prov ...
     gnop destroy [-fv] prov ...
     gnop list
     gnop status
     gnop load
     gnop unload

DESCRIPTION
     The gnop utility is used for setting up transparent providers on existing
     ones.  Its main purpose is testing other GEOM classes, as it allows
     forced provider removal and I/O error simulation with a given probabil-
     ity.  It is also a good starting point for implementing new GEOM classes.

     The first argument to gnop indicates an action to be performed:

     create     Set up a transparent provider on the given devices.  If the
                operation succeeds, the new provider should appear with name
                /dev/<dev>.nop.  The kernel module geom_nop.ko will be loaded
                if it is not loaded already.

     configure  Configure existing transparent provider.  At the moment it is
                only used for changing failure probability.  The kernel module
                geom_nop.ko will be loaded if it is not loaded already.

     destroy    Turn off the given transparent providers.

     list       See geom(8).

     status     See geom(8).

     load       See geom(8).

     unload     See geom(8).

     Additional options:

     -f           Force the removal of the specified provider.

     -f failprob  Specifies failure probability in percentage.

     -o offset    Where to begin on the original provider.

     -s size      Size of the transparent provider.

     -S secsize   Sector size of the transparent provider.

     -v           Be more verbose.

SYSCTL VARIABLES
     The following sysctl(8) variables can be used to control the behavior of
     the NOP GEOM class.  The default value is shown next to each variable.

     kern.geom.nop.debug: 0
             Debug level of the NOP GEOM class.  This can be set to a number
             between 0 and 2 inclusive.  If set to 0 minimal debug information
             is printed, and if set to 2 the maximum amount of debug informa-
             tion is printed.

EXIT STATUS
     Exit status is 0 on success, and 1 if the command fails.

EXAMPLES
     The following example shows how to create a transparent provider for disk
     /dev/da0 with 50% failure probability, and how to destroy it.

           gnop create -v -f 50 da0
           gnop destroy -v da0.nop

SEE ALSO
     geom(4), geom(8)

HISTORY
     The gnop utility appeared in FreeBSD 5.3.

AUTHORS
     Pawel Jakub Dawidek <pjdATFreeBSD.org>

BSD                              May 21, 2004                              BSD