config root man

.\" Copyright (c) 2004-2006 Pawel Jakub Dawidek <pjd@FreeBSD.org>
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.\" $FreeBSD: release/9.1.0/sbin/geom/class/nop/gnop.8 197274 2009-09-17 13:04:46Z brueffer $
.\"
.Dd September 17, 2009
.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 e Ar error
.Op Fl o Ar offset
.Op Fl r Ar rfailprob
.Op Fl s Ar size
.Op Fl S Ar secsize
.Op Fl w Ar wfailprob
.Ar dev ...
.Nm
.Cm configure
.Op Fl v
.Op Fl e Ar error
.Op Fl r Ar rfailprob
.Op Fl w Ar wfailprob
.Ar prov ...
.Nm
.Cm destroy
.Op Fl fv
.Ar prov ...
.Nm
.Cm reset
.Op Fl v
.Ar prov ...
.Nm
.Cm list
.Nm
.Cm status
.Nm
.Cm load
.Nm
.Cm unload
.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 forced provider
removal and I/O error simulation with a given probability.
It also gathers the following statistics: number of read requests, number of
write requests, number of bytes read and number of bytes written.
In addition, it can be used as 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
Set up a transparent provider on the given devices.
If the operation succeeds, the new provider should appear with name
.Pa /dev/ Ns Ao Ar dev Ac Ns Pa .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.
.It Cm destroy
Turn off the given transparent providers.
.It Cm reset
Reset statistics for the given transparent providers.
.It Cm list
See
.Xr geom 8 .
.It Cm status
See
.Xr geom 8 .
.It Cm load
See
.Xr geom 8 .
.It Cm unload
See
.Xr geom 8 .
.El
.Pp
Additional options:
.Bl -tag -width ".Fl r Ar rfailprob"
.It Fl e Ar error
Specifies the error number to return on failure.
.It Fl f
Force the removal of the specified provider.
.It Fl o Ar offset
Where to begin on the original provider.
.It Fl r Ar rfailprob
Specifies read failure probability in percent.
.It Fl s Ar size
Size of the transparent provider.
.It Fl S Ar secsize
Sector size of the transparent provider.
.It Fl w Ar wfailprob
Specifies write failure probability in percent.
.It Fl v
Be more verbose.
.El
.Sh SYSCTL VARIABLES
The following
.Xr sysctl 8
variables can be used to control the behavior of the
.Nm NOP
GEOM class.
The default value is shown next to each variable.
.Bl -tag -width indent
.It Va kern.geom.nop.debug : No 0
Debug level of the
.Nm 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.
.El
.Sh EXIT STATUS
Exit status is 0 on success, and 1 if the command fails.
.Sh EXAMPLES
The following example shows how to create a transparent provider for disk
.Pa /dev/da0
with 50% write failure probability, and how to destroy it.
.Bd -literal -offset indent
gnop create -v -w 50 da0
gnop destroy -v da0.nop
.Ed
.Pp
The traffic statistics for the given transparent providers can be obtained
with the
.Cm list
command.
The example below shows the number of bytes written with
.Xr newfs 8 :
.Bd -literal -offset indent
gnop create da0
newfs /dev/da0.nop
gnop list
.Ed
.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