NAME
gnop —
control utility for NOP GEOM
class
SYNOPSIS
gnop |
create [-v]
[-e error]
[-o offset]
[-p stripesize]
[-P stripeoffset]
[-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
Thegnop 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 statistics on the number of read, write, delete,
getattr, flush, and other requests, and the number of bytes read and written.
gnop can also 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:
-eerror- Specifies the error number to return on failure.
-f- Force the removal of the specified provider.
-ooffset- Where to begin on the original provider.
-pstripesize- Value of the stripesize property of the transparent provider.
-Pstripeoffset- Value of the stripeoffset property of the transparent provider.
-rrfailprob- Specifies read failure probability in percent.
-ssize- Size of the transparent provider.
-Ssecsize- Sector size of the transparent provider.
-wwfailprob- 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 variable.
- kern.geom.nop.debug: 0
- Debug level of the
NOPGEOM 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
HISTORY
The gnop utility appeared in
FreeBSD 5.3.
AUTHORS
Pawel Jakub Dawidek <pjd@FreeBSD.org>