.\" Copyright (c) 2004 Pawel Jakub Dawidek <pjd@FreeBSD.org>
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.\" $FreeBSD$
.\"
.Dd May 21, 2004
.Dt GNOP 8
.Os
.Sh NAME
.Nm gnop
.Nd "control utility for NOP GEOM class"
.Sh SYNOPSIS
.Nm
.Cm create
.Op Fl v
.Op Fl f Ar failprob
.Ar dev1
.Op Ar dev2 Op Ar ...
.Nm
.Cm configure
.Op Fl v
.Op Fl f Ar failprob
.Ar prov1
.Op Ar prov2 Op Ar ...
.Nm
.Cm destroy
.Op Fl fv
.Ar prov1
.Op Ar prov2 Op Ar ...
.Nm
.Cm list
.Op Ar prov Op Ar ...
.Nm
.Cm load
.Op Fl v
.Nm
.Cm unload
.Op Fl v
.Sh DESCRIPTION
The
.Nm
utility is used for setting up transparent providers on existing ones.
Its main purpose is testing other GEOM classes, as it allows force providers
removal and I/O errors simulation with a given probability.
It is also a good starting point for implementing new GEOM classes.
.Pp
The first argument to
.Nm
indicates an action to be performed:
.Bl -tag -width ".Cm configure"
.It Cm create
Setup a transparent provider on the given devices.
If operation succeded, new provider should appear with name
.Pa /dev/<dev>.nop .
The kernel module
.Pa geom_nop.ko
will be loaded if it is not loaded already.
.It Cm configure
Configure existing transparent provider. At the moment it is only used
for changing failure probability.
The kernel module
.Pa geom_nop.ko
will be loaded if it is not loaded already.
.It Cm destroy
Turn off the given transparent providers.
.It Cm list
List all or the given currently configured providers.
.It Cm load
Load
.Pa geom_nop.ko
kernel module.
.It Cm unload
Unload
.Pa geom_nop.ko
kernel module.
.El
.Pp
Additional options:
.Bl -tag -width ".Fl f Ar failprob"
.It Fl f
Force the removal of the specified provider.
.It Fl f Ar failprob
Specifies failure probability in percentage.
.It Fl v
Be more verbose.
.El
.Sh EXAMPLES
The following example shows how to create a transparent provider for disk
.Pa /dev/da0
with 50% failure probability and destroy it.
.Bd -literal -offset indent
gnop create -v -f 50 da0
gnop destroy -v da0.nop
.Ed
.Sh DIAGNOSTICS
Exit status is 0 on success, and 1 if the command fails.
.Sh SEE ALSO
.Xr geom 4 ,
.Xr geom 8
.Sh HISTORY
The
.Nm
utility appeared in
.Fx 5.3 .
.Sh AUTHORS
.An Pawel Jakub Dawidek Aq pjd@FreeBSD.org