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27 .Dd September 15, 2015
32 .Nd "control utility for NOP GEOM class"
39 .Op Fl p Ar stripesize
40 .Op Fl P Ar stripeoffset
72 utility is used for setting up transparent providers on existing ones.
73 Its main purpose is testing other GEOM classes, as it allows forced provider
74 removal and I/O error simulation with a given probability.
75 It also gathers the following statistics: number of read requests, number of
76 write requests, number of bytes read and number of bytes written.
77 In addition, it can be used as a good starting point for implementing new GEOM
82 indicates an action to be performed:
83 .Bl -tag -width ".Cm configure"
85 Set up a transparent provider on the given devices.
86 If the operation succeeds, the new provider should appear with name
87 .Pa /dev/ Ns Ao Ar dev Ac Ns Pa .nop .
90 will be loaded if it is not loaded already.
92 Configure existing transparent provider.
93 At the moment it is only used for changing failure probability.
95 Turn off the given transparent providers.
97 Reset statistics for the given transparent providers.
113 .Bl -tag -width ".Fl r Ar rfailprob"
115 Specifies the error number to return on failure.
117 Force the removal of the specified provider.
119 Where to begin on the original provider.
120 .It Fl p Ar stripesize
121 Value of the stripesize property of the transparent provider.
122 .It Fl P Ar stripeoffset
123 Value of the stripeoffset property of the transparent provider.
124 .It Fl r Ar rfailprob
125 Specifies read failure probability in percent.
127 Size of the transparent provider.
129 Sector size of the transparent provider.
130 .It Fl w Ar wfailprob
131 Specifies write failure probability in percent.
138 variables can be used to control the behavior of the
141 The default value is shown next to each variable.
142 .Bl -tag -width indent
143 .It Va kern.geom.nop.debug : No 0
147 This can be set to a number between 0 and 2 inclusive.
148 If set to 0, minimal debug information is printed.
149 If set to 1, basic debug information is logged along with the I/O requests
150 that were returned as errors.
151 If set to 2, the maximum amount of debug information is printed including
155 Exit status is 0 on success, and 1 if the command fails.
157 The following example shows how to create a transparent provider for disk
159 with 50% write failure probability, and how to destroy it.
160 .Bd -literal -offset indent
161 gnop create -v -w 50 da0
162 gnop destroy -v da0.nop
165 The traffic statistics for the given transparent providers can be obtained
169 The example below shows the number of bytes written with
171 .Bd -literal -offset indent
185 .An Pawel Jakub Dawidek Aq Mt pjd@FreeBSD.org