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GNOP(8) System Manager's Manual GNOP(8) NAME gnop -- control utility for NOP GEOM class SYNOPSIS gnop create [-v] [-e error] [-o offset] [-r rfailprob] [-s size] [-S secsize] [-w wfailprob] dev ... gnop configure [-v] [-e error] [-r rfailprob] [-w wfailprob] 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 exist- ing 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 re- quests, 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. 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: -e error Specifies the error number to return on failure. -f Force the removal of the specified provider. -o offset Where to begin on the original provider. -r rfailprob Specifies read failure probability in percent. -s size Size of the transparent provider. -S secsize Sector size of the transparent provider. -w wfailprob Specifies write failure probability in percent. -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 vari- able. 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 informa- tion is printed. If set to 1, basic debug information is logged along with the I/O requests that were returned as er- rors. If set to 2, the maximum amount of debug information is printed including all I/O requests. 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% write failure probability, and how to destroy it. gnop create -v -w 50 da0 gnop destroy -v da0.nop The traffic statistics for the given transparent providers can be ob- tained with the list command. The example below shows the 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 <pjd@FreeBSD.org> FreeBSD 10.0 April 14, 2013 GNOP(8)
NAME | SYNOPSIS | DESCRIPTION | SYSCTL VARIABLES | EXIT STATUS | EXAMPLES | SEE ALSO | HISTORY | AUTHORS
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