gnop(8) [freebsd man page]

GNOP(8) 						    BSD 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 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.

     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 information is
	     printed.  If set to 1, basic debug information is logged along with the I/O requests that were returned as errors.  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 obtained 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>

BSD
								  April 14, 2013							       BSD

Check Out this Related Man Page

GSCHED(8)						    BSD System Manager's Manual 						 GSCHED(8)

NAME

     gsched -- control utility for disk scheduler GEOM class

SYNOPSIS

     gsched create [-v] [-a algorithm] provider ...
     gsched insert [-v] [-a algorithm] provider ...
     gsched configure [-v] [-a algorithm] node ...
     gsched destroy [-fv] node ...
     gsched reset [-v] node ...
     gsched { list | status | load | unload }

DESCRIPTION

     The gsched utility (also callable as geom sched ...) changes the scheduling policy of the requests going to a provider.

     The first argument to gsched indicates an action to be performed:

     create	Create a new provider and geom node using the specified scheduling algorithm.  algorithm is the name of the scheduling algorithm
		used for the provider.	Available algorithms include: rr, which implements anticipatory scheduling with round robin service among
		clients; as, which implements a simple form of anticipatory scheduling with no per-client queue.

		If the operation succeeds, the new provider should appear with name /dev/<dev>.sched..	The kernel module geom_sched.ko will be
		loaded if it is not loaded already.

     insert	Operates as "create", but the insertion is "transparent", i.e. the existing provider is rerouted to the newly created geom, which
		in turn forwards requests to the existing geom.  This operation allows one to start/stop a scheduling service on an already exist-
		ing provider.

		A subsequent "destroy" will remove the newly created geom and hook the provider back to the original geom.

     configure	Configure existing scheduling provider.  It supports the same options as the create command.

     destroy	Destroy the geom specified in the parameter.

     reset	Do nothing.

     list | status | load | unload
		See geom(8).

     Additional options:

     -f  Force the removal of the specified provider.

     -v  Be more verbose.

SYSCTL VARIABLES

     The following sysctl(8) variables can be used to control the behavior of the SCHED GEOM class.  The default value is shown next to each vari-
     able.

     kern.geom.sched.debug: 0
	     Debug level of the SCHED 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.

EXIT STATUS

     Exit status is 0 on success, and 1 if the command fails.

EXAMPLES

     The following example shows how to create a scheduling provider for disk /dev/ada0, and how to destroy it.

	   # Load the geom_sched module:
	   kldload geom_sched
	   # Load some scheduler classes used by geom_sched:
	   kldload gsched_rr
	   # Configure device ada0 to use scheduler "rr":
	   geom sched insert -a rr ada0
	   # Now provider ada0 uses the "rr" algorithm;
	   # the new geom is ada0.sched.
	   # Remove the scheduler on the device:
	   geom sched destroy -v ada0.sched.

SEE ALSO

     geom(4), geom(8)

HISTORY

     The gsched utility first appeared in FreeBSD 8.1.

AUTHORS

     Fabio Checconi <fabio@FreeBSD.org>
     Luigi Rizzo <luigi@FreeBSD.org>

BSD
								   July 26, 2012							       BSD

Linux and UNIX Man Pages

gnop(8) [freebsd man page]

Check Out this Related Man Page

Featured Tech Videos