2 .\" Copyright (c) 2010 Edward Tomasz Napierala
3 .\" All rights reserved.
5 .\" Redistribution and use in source and binary forms, with or without
6 .\" modification, are permitted provided that the following conditions
8 .\" 1. Redistributions of source code must retain the above copyright
9 .\" notice, this list of conditions and the following disclaimer.
10 .\" 2. Redistributions in binary form must reproduce the above copyright
11 .\" notice, this list of conditions and the following disclaimer in the
12 .\" documentation and/or other materials provided with the distribution.
14 .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 .\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR THE VOICES IN HIS HEAD BE
18 .\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
19 .\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
20 .\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
21 .\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
22 .\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
23 .\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
24 .\" POSSIBILITY OF SUCH DAMAGE.
33 .Nd "control utility for CACHE GEOM class"
84 utility is used to control GEOM cache, which can
85 speed up read performance by sending fixed size
86 read requests to its consumer. It has been developed to address
87 the problem of a horrible read performance of a 64k blocksize FS
88 residing on a RAID3 array with 8 data components, where a single
89 disk component would only get 8k read requests, thus effectively
90 killing disk performance under high load.
92 Caching can be configured using two different methods:
98 method, no metadata are stored on the devices, so the cached
99 device has to be configured by hand every time it is needed.
102 method uses on-disk metadata to detect devices.
103 Once devices are labeled, they will be automatically detected and
106 The first argument to
108 indicates an action to be performed:
109 .Bl -tag -width ".Cm destroy"
111 Cache the given devices with specified
118 will be loaded if it is not loaded already.
120 Cache the given devices with the specified
124 method, where metadata are stored in every device's last sector.
127 will be loaded if it is not loaded already.
129 Turn off existing cache device by its
131 This command does not touch on-disk metadata!
136 Clear metadata on the given devices.
138 Dump metadata stored on the given devices.
154 .Bl -tag -width indent
156 Force the removal of the specified cache device.
163 variables can be used to control the behavior of the
166 The default value is shown next to each variable.
167 .Bl -tag -width indent
168 .It Va kern.geom.cache.used_hi : No 20
169 .It Va kern.geom.cache.used_lo : No 5
170 .It Va kern.geom.cache.idletime : No 5
171 .It Va kern.geom.cache.timeout : No 10
172 .It Va kern.geom.cache.enable : No 1
173 .It Va kern.geom.cache.debug : No 0
177 This can be set to a number between 0 and 3 inclusive.
178 If set to 0 minimal debug information is printed, and if set to 3 the
179 maximum amount of debug information is printed.
182 Exit status is 0 on success, and 1 if the command fails.
192 .An Ruslan Ermilov Aq ru@FreeBSD.org