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gnop
GNOP(8) FreeBSD 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 reset [-v] 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 also gathers the following statistics: number of read requests,
number of write requests, number of read bytes and number of wrote bytes.
In addition, it can be used as a good starting point for implementing new
GEOM class.
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.
destroy Turn off the given transparent providers.
reset Reset statistics for 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
The traffic statistics for the given transparent providers we can get
with list command. Example below shows how can we obtain number of bytes
written with newfs(8):
gnop create da0
newfs /dev/da0.nop
gnop list
SEE ALSO
geom(4), geom(8)
HISTORY
The gnop utility appeared in FreeBSD 5.3.
AUTHORS
Pawel Jakub Dawidek <pjdATFreeBSD.org>
FreeBSD 6.2 May 21, 2004 FreeBSD 6.2
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