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gnop - "control utility for NOP GEOM class"


Sysctl Variables
Exit Status
See Also


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


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 probability. 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.


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 information is printed.


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


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


geom(4), geom(8)



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