5af4e2f1be
Change the "count_until_fail" option of gnop, now it enables the failing rating instead of setting them to 100%. The original patch introduced the new flag, which sets the fail/rate to 100% after N requests. In some cases, we don't want to have 100% of failure probabilities. We want to start failing at some point. For example, on the early stage, we may like to allow some read/writes requests before having some requests delayed - when we try to mount the partition, or when we are trying to import the pool. Another case may be to check how scrub in ZFS will behave on different stages. This allows us to cover more cases. The previous behavior still may be configured. Reviewed by: kib Differential Revision: https://reviews.freebsd.org/D22632
214 lines
5.8 KiB
Groff
214 lines
5.8 KiB
Groff
.\" Copyright (c) 2004-2006 Pawel Jakub Dawidek <pjd@FreeBSD.org>
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd December 29, 2019
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.Dt GNOP 8
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.Os
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.Sh NAME
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.Nm gnop
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.Nd "control utility for NOP GEOM class"
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.Sh SYNOPSIS
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.Nm
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.Cm create
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.Op Fl v
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.Op Fl c Ar count_until_fail
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.Op Fl d Ar delaymsec
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.Op Fl e Ar error
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.Op Fl o Ar offset
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.Op Fl p Ar stripesize
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.Op Fl P Ar stripeoffset
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.Op Fl q Ar rdelayprob
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.Op Fl r Ar rfailprob
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.Op Fl s Ar size
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.Op Fl S Ar secsize
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.Op Fl w Ar wfailprob
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.Op Fl x Ar wdelayprob
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.Op Fl z Ar physpath
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.Op Fl Z Ar gnopname
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.Ar dev ...
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.Nm
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.Cm configure
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.Op Fl v
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.Op Fl c Ar count_until_fail
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.Op Fl d Ar delaymsec
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.Op Fl e Ar error
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.Op Fl q Ar rdelayprob
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.Op Fl r Ar rfailprob
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.Op Fl w Ar wfailprob
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.Op Fl x Ar wdelayprob
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.Ar prov ...
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.Nm
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.Cm destroy
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.Op Fl fv
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.Ar prov ...
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.Nm
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.Cm reset
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.Op Fl v
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.Ar prov ...
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.Nm
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.Cm list
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.Nm
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.Cm status
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.Nm
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.Cm load
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.Nm
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.Cm unload
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.Sh DESCRIPTION
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The
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.Nm
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utility is used for setting up transparent providers on existing ones.
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Its main purpose is testing other GEOM classes, as it allows forced provider
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removal and I/O error simulation with a given probability.
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It also gathers statistics on the number of read, write, delete,
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getattr, flush, and other requests, and the number of bytes read and written.
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.Nm
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can also be used as a good starting point for implementing new GEOM
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classes.
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.Pp
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The first argument to
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.Nm
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indicates an action to be performed:
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.Bl -tag -width ".Cm configure"
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.It Cm create
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Set up a transparent provider on the given devices.
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If the operation succeeds, the new provider should appear with name
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.Pa /dev/ Ns Ao Ar dev Ac Ns Pa .nop .
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The kernel module
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.Pa geom_nop.ko
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will be loaded if it is not loaded already.
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.It Cm configure
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Configure existing transparent provider.
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At the moment it is only used for changing failure probability.
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.It Cm destroy
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Turn off the given transparent providers.
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.It Cm reset
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Reset statistics for the given transparent providers.
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.It Cm list
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See
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.Xr geom 8 .
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.It Cm status
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See
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.Xr geom 8 .
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.It Cm load
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See
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.Xr geom 8 .
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.It Cm unload
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See
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.Xr geom 8 .
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.El
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.Pp
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Additional options:
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.Bl -tag -width "-c count_until_fail"
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.It Fl c Ar count_until_fail
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Specifies the number of I/O requests to allow before setting the read, write and
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delay failure probabilities.
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.It Fl d Ar delaymsec
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Specifies the delay of the requests in milliseconds.
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Note that requests will be delayed before they are sent to the backing device.
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.It Fl e Ar error
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Specifies the error number to return on failure.
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.It Fl f
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Force the removal of the specified provider.
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.It Fl o Ar offset
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Where to begin on the original provider.
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.It Fl p Ar stripesize
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Value of the stripesize property of the transparent provider.
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.It Fl P Ar stripeoffset
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Value of the stripeoffset property of the transparent provider.
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.It Fl q Ar rdelayprob
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Specifies read delay probability in percent.
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.It Fl r Ar rfailprob
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Specifies read failure probability in percent.
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.It Fl s Ar size
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Size of the transparent provider.
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.It Fl S Ar secsize
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Sector size of the transparent provider.
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.It Fl w Ar wfailprob
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Specifies write failure probability in percent.
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.It Fl v
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Be more verbose.
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.It Fl x Ar wdelayprob
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Specifies write delay probability in percent.
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.It Fl z Ar physpath
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Physical path of the transparent provider.
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.It Fl Z Ar gnopname
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The name of the new provider.
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The suffix
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.Dq .nop
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will be appended to the provider name.
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.El
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.Sh SYSCTL VARIABLES
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The following
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.Xr sysctl 8
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variables can be used to control the behavior of the
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.Nm NOP
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GEOM class.
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The default value is shown next to each variable.
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.Bl -tag -width indent
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.It Va kern.geom.nop.debug : No 0
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Debug level of the
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.Nm NOP
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GEOM class.
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This can be set to a number between 0 and 2 inclusive.
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If set to 0, minimal debug information is printed.
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If set to 1, basic debug information is logged along with the I/O requests
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that were returned as errors.
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If set to 2, the maximum amount of debug information is printed including
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all I/O requests.
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.El
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.Sh EXIT STATUS
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Exit status is 0 on success, and 1 if the command fails.
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.Sh EXAMPLES
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The following example shows how to create a transparent provider for disk
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.Pa /dev/da0
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with 50% write failure probability, and how to destroy it.
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.Bd -literal -offset indent
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gnop create -v -w 50 da0
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gnop destroy -v da0.nop
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.Ed
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.Pp
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The traffic statistics for the given transparent providers can be obtained
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with the
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.Cm list
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command.
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The example below shows the number of bytes written with
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.Xr newfs 8 :
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.Bd -literal -offset indent
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gnop create da0
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newfs /dev/da0.nop
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gnop list
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.Ed
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.Sh SEE ALSO
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.Xr geom 4 ,
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.Xr geom 8
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.Sh HISTORY
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The
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.Nm
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utility appeared in
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.Fx 5.3 .
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.Sh AUTHORS
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.An Pawel Jakub Dawidek Aq Mt pjd@FreeBSD.org
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